Update index.js

Fixes a bug when requesting many covers.

The URL becomes something like:
```
http://ws.audioscrobbler.com/2.0/?method=album.getinfo&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json&artist=Pendulum&album=Watercolour&api_key=3f6675c78c4054c7ee6e361a06ec6cff&format=json```

Error: request URI too large