feature #3194: Change image upload to use resumable library

Now images are uploaded in chunks and they are retried when
an error happens
fearure #3194: bug assembling the image file
feature #3194: show add file button in the upload wizard
feature #3194: fix malformed input tag
feature #3194: use resumable.js for files upload
feature #3194: delete old unused code
feature #3194: Remove file uploader and add resumablejs dependency
feature #3194: Fix upload error message format
feature #3194: Do not remove event target when the file input changes
Merge branch 'feature-3194'
Add upload support files support