Thanksgiving Update!, fixes #3, #4, #13

- fixed the AddPlaylist button so that it updates the Playlist List
- fixed added Delete key listeners to the Playlist List and the JTable.
When you hit the delete key, it removes the selected images from the
selected playlist/library, or removes the selected playlist
- added Library to the sidebar
- selecting a playlist in the sidebar changes what is displayed in the
JTable
Merge pull request #14 from Kpaxx/Add-Playlist-Button

Thanksgiving Update!, fixes #3, #4, #13