Code Style: Clean up Gruntfile object syntax

Remove spaces before colons in object literals
Code style: strings should use single quote marks
Code style: Standardize function argument spacing
Add WP core JSHint options and alter code to pass

Note: the testing directory jshintrc also lists "wp" and "sinon" as global
variables, although these are not present in WP's testing jshintrc.
Merge pull request #9 from kadamwhite/standardize-formatting

Standardize formatting