chore(grunt): adds grunt-conventional-changelog plugin

this plugin lets you auto-generate changelogs based on given commit
history

you commit messages have to follow the same conventions that are used
in this commit

for more information see http://github.com/btford/grunt-conventional-changelog
Make $on chainable
Merge branch 'grunt-conventional-changelog-support' of https://github.com/PascalPrecht/angularFire into PascalPrecht-grunt-conventional-changelog-support

Conflicts:
	Gruntfile.js
	package.json
Move angular-mocks and observe-js to devDependencies
Fixed some typos
Fixes #255 - orderByPriority always returns an array
Merge pull request #258 from katowulf/master

Fixes #255 - orderByPriority always returns an array
Merge pull request #257 from sanderboom/typos

Fixed some typos
Add method $getRef to $firebase objects, fixes #252
Add note to fix second timeout by referencing Github issue
Add $update method, fixes #238
bump version to 0.7.0
Returning the promise from $transaction
Merge pull request #269 from jmcclell/patch-1

Returning the promise from $transaction
Added MockFirebase for test units
Upgrading FirebaseSimpleLogin to 1.3.0
Finished MockFirebase testing and upgrade of existing unit tests
Remove unnecessary sinon include
Added getPriority() stub to snashots and prevChild to child_added/moved events
Added test units for orderByPriority