deleted white spaces
deleted white spaces for rails best practices.
Deleted admin_helper.rb --> not used
Deleted user_helper.rb --> not used
Merge pull request #44 from felixsoum/backend-dev

Backend dev
Add more narrative fixtures
Add .mp4 to accepted audio formats
Delete .last_run.json
Merge remote-tracking branch 'origin/master-rails_best_practices'

Conflicts:
	app/controllers/narratives_controller.rb
	app/views/narratives/play.html.erb
Merge branch 'fixture'
Fix narrative delete because of absolute path to relative path
Update error message when uploading wrong format
Fix fixtures containing invalid files
Add Gemnasium badge