[WIP] Replace Bootstrap file uploader with ember-plupload component

[IanVS]

Using ember-plupload should prevent the files queued for upload from being lost when an album is added, as the upload queue is maintained across routes. (fixes #11)

Remaining work:

• [x] Add submit button and action
• [x] Test against server API
• [x] Ensure that file deletion happens correctly
• [ ] Cache CORS preflight response
• [ ] Further UI/UX improvements
  • [x] Prevent upload button press without an album selected
  • [ ] Change behavior on hover when dragging in a file
  • [x] Make sure that file can be dragged to any location inside dropzone
• [ ] Extract component from template into ember component

[IanVS]

Looks like setting the max-age of the preflight CORS response is not yet possible in Sails: https://github.com/balderdashy/sails/issues/2345#issuecomment-100075124

[IanVS]

@mgenev my next step will likely be to extract the uploader/preview that we've created here into its own component. Do you see any other changes I should make?

[mgenev]

I can't think of any changes right now. Great work so far. I'll probably end up styling as I think of ideas. If you have any you can feel free to revisit it any time.

[mgenev]

thinking of merging and adding improvements as we go forward. any objections?

[IanVS]

Sure, that's fine with me.