refactor(track): Break apart track card template and include it
feat(playlist): Add tracks
refactor(playlist-directive): Move track-adding logic to factory

Add unit tests
Add annotations
feat(playlist): Add angular-ui-sortable for sorting tracks in a playlist
feat(playlist): Add ability to sort tracks in a playlist

[#14]
Merge pull request #53 from ilyakam/feat-14-sort-tracks

Add ability to sort tracks in a playlist