Display a notification when successfully installing a package

Improve wording in notification
Update CONTRIBUTING.md
Fix return value of package factory, fix tests
Test parsing website from package url
updated Kiwi to 2.1 and used string matchers
tested parsing revisions
added some more package tests
tested abstract installing stuff
renamed local packages. extracted completion blocks
Made ibactions names more consistent
made packages reload each time the window is opened.
fixed specs
Only display notification on successfull install
shoot for 1 expectation per spec
Reference @katralli's post on debugging Xcode plugins
Add version label to ATZ window
Add rake task for updating atz version
os x `sed` doesn't support -i??
Create custom view for version label
Show revision as version label tooltip
Align version label to right of the window when resizing