Update assets to jQuery-File-Upload v9.12.5

[peterwake]

Hi @tors and @felixbuenemann - now I have learned how to squash commits!

For anyone else doing this (assuming you have 3 commits to squash into one, and you had been working on your forked master):
git rebase -i HEAD~3
This will take you into a vim editor - use i to edit (in my case, didn't use squash, used fixup) , and then escape to get back the command line. and type :wq to write and quit the editor
git push origin master --force
You will need to cancel your previous pull request and create a new one.

[tors]

Looks good! Thanks for the contribution! If there are no issues, I'm gonna go ahead and merge this pull request and push to rubygems. cc @felixbuenemann

[felixbuenemann]

@tors