chore(build): Initial stab at Grunt skeleton

A case study in how *not* to do pull requests...

But we should now have a shared precommit-hook which runs lint tasks whenever you try and commit some code.
JSHint and JSCS rules are up for negotiation.

FIxes #31
Fixes #17 
FIxes #13 
Fixes #12 
Fixes #11 
Yeah, I definitely think that the Grunt flow and npm scripts will need some documentation (either in the GH wiki, README, or CONTRIBUTING doc). I'll probably do that in a separate [near] future PR once I sort out how to glue Sass+Autoprefixer+Watch into this mix. And then I think we're looking at using a bump/version task which will generate the changelog+authors files for us, bump the version numbers in package.json and then push the release to GitHub (we do something similar in fxa-content-server).

But I 1000% agree. Docs are crucial to this project and we'll need to document everything thoroughly for future travelers.