Songs in the profile page now show in order of last updated. Should we show those dates on the page?
Sort songs on the user#show page in descending order by date_updated

Merge branch 'feature/sort-songs-in-user-profile-by-date-updated'
add version model
fix bug in VersionTrack
VersionTrack rows are correctly inserted based on number of tracks. Todo: Give new Versions a song_id, a message, and a slug
song_id and message now passed to version when a new version is created. Todo: Does a version_track_id need to be assigned to Version? Edit show page so that the latest version in a song is shown on the page. Later todo: add a dropdown menu where a user can select from versions to display.
fix delete track route, add hidden:boolean to tracks
tracks are no long deleted, rather their hidden boolean value is set to true which prevents them from being displayed on the page
Remove version_tracks_id column from Version table
add form for selecting versions. todo: sort items in list in descending order by date created, and implement JavaScript to update the page to username/songname/versions/:id every time a new version is selected
track versions now sort by updated_at desc in the dropdown menu
moved sorting logic out of the view. Bad Taylor!
user can now access versions by /:username/:songname/:versionid
add javascript to allow seamless picking of versions
Merge branch 'master' of https://github.com/clamstew/jamhub
Merging the versioning feature with the master.

Merge branch 'features/versioning'