Show version of Alcatraz in title bar

## Changes

- Add version constant (currently in `ATZVersionLabel.m`)
- Add task to update version constant and `git tag` a revision with new version number
- Show version in window title bar

![Version indicator added](http://f.cl.ly/items/0E3t3G0Q3p0m2t0W083Y/Screen%20Shot%202013-05-16%20at%2010.56.15%20PM.png)