Upgrade to ruby 2.1

- fix rubocop warnings
 - disable rubocop since some warnings should
   not be fixed and cannot be silenced; in particular trailing
   comma's in multiline hashes.
Maybe fix yml?
Update travis ruby version
Merge branch 'upgrade-to-ruby-2.1' into drag-drop-stories-in-react
(minor) spacing
Fix rubocop warnings
Update mime-type to be more logical
Replace log with console.log
Hide story when moving
Fix dragover handler

- getData only works on drop according to spec
 - effectAllowed & dropEffect should be on the dataTransfer object, not
the event
Clean up whitespace
Update TODO
More flexible mimetype detection
(minor) syntax cleanup
Pass around position as object