Removed unused _.extend to grunt.config()

Tests passing.

Removed this _.extend() call in order to avoid errors on grunt when applying a custom wrap.

Error was: 

```
>> A special character was detected in this template. Inside template tags, the
>> \n and \r special characters must be escaped as \\n and \\r. (grunt 0.4.0+)
Warning: An error occurred while processing a template (Unexpected token ILLEGAL). Us
ed --force, continuing.
```