Refactor VC. Autoupdate packages on Xcode startup.

This PR consists of 2 commits.
- In first one I moved all common constants to ATZConstants and ATZUtils. Also I fixed usages of `stringByAppending*` when composing paths using path extension.
- In second commit I moved all business logic from view controller to `ATZPackageUtils` which gave ability to update packages on Xcode startup rather then when Alcatraz window is opened. Also timer will be scheduled to requests updates every hour. And all UI/IBOutlets stuff was moved under category in implementation file to clear VC header file.

Tested in Xcode 6 GM.

P.S. This is not random PR. Other PRs based on this one, which will extend Alcatraz functionality, will be sent.