Enable source maps for CoffeeScript using the --maps=true option

This allows sourcemaps to be used so that developers can debug the CoffeeScript directly, rather than the JS generated from the CS.

Building:
```
grunt test:conf --maps=true
```

Watching:
```
grunt watch --maps=true
```

This is the same as https://github.com/RallySoftware/appsdk/pull/169, but for app-catalog