Updating `.gitignore`

Updating to version 2.1 of the source page, which includes Xcode 5
uniqueness.
Adding *.xccheckout as an ignore file.
Adding * to ignore.
Store track information in a dedicated track object
Merge branch 'git-ignore' of https://github.com/TheSeg/Spotify-Notifications into TheSeg-git-ignore

* 'git-ignore' of https://github.com/TheSeg/Spotify-Notifications:
  Adding * to ignore.
  Adding *.xccheckout as an ignore file.
  Updating `.gitignore`