Fixed small typo

Was doing a quick read through and saw that there was a small typo.
Merge pull request #3 from justinchmura/patch-1

Fixed small typo
Cleanup leftovers.

Remove leftover require('rsvp') from refactoring in mustbe/core.js
Cleanup leftovers.... again.
Merge pull request #4 from nicholaswyoung/master

Cleanup leftovers.