Update for 0.6.1

@garyb @joneshf @jdegoes Could you please review?

To parse multiple guards, every guard needs to be equally indented, and in 0.6.1 this means that the body of the guard needs to be more indented than its expression, which breaks `purescript-lists` and `purescript-maps`.

This also updates the Gruntfile to use `grunt-purescript-0.6.0` and `pscDocs`.