Session #1.

- Keeps track of selected tracks
- Keeps track of the selected track count
- Enables the create playlist button when there's at least
  one track selected.
lirabry.js -> library.js
ngRoute replaced with dotJEM/angular-routing.
Creating Playlists.
Implemented Nested Routes.
Smaller fixes. README.md ready.
Code Exercise. :)
Animated GIF all the things.
/#/ redirects to /#/library
1 second delay rendering /#/playlist/:id