feat(backend, frontend): add rough skeleton support for file uploads

  File upload skeleton includes:
  * Add backend endpoint for file uploads
  * File uploads save to filesystem currently
  * Install angular-file-upload module
  * Drag an drop zone in candy save modal
  * Queue display below drop zone with file upload operations buttons
  * File meta data are added to candy resource and saved to CouchDB
Merge pull request #13 from ghachey/fileupload

feat(backend, frontend): add rough skeleton support for file uploads