updates grunt-neuter version from 0.5.0 to 0.6.0

A problem I ran into with the old version (0.5.0) of grunt-neuter is not having the ability to have require statements without semicolons:

```javascript
require('a')
require('b')
```

This wouldn't compile correctly unless I added semicolons:

```javascript
require('a');
require('b');
```