minor fixes
got direct upload to s3 via ajax
loads music file from database if one is already added
identifies the correct song for each show
Few small timeline CSS and JS changes
Tidied up shows/edit and shows controller
Merge branch 'jack' into develop

Conflicts:
	app/assets/javascripts/tracks.js.coffee
	app/controllers/shows_controller.rb
	app/views/shows/edit.html.erb
	db/schema.rb
	vendor/assets/stylesheets/timeline.css
Merged with some bug fixes. Semi-working
bug fixes mainly on timeline
Fixed the snap to seconds bug.