Reset file input after handling the file (fixes #22)

When selecting the same file twice, the change event doesn't fire
the second time. Resetting the input value makes sure, the event
fires again.
Merge pull request #26 from galfert/fix_same_file_upload

Reset file input after handling the file (fixes #22)
Merge branch 'master' into fix_webkit_dragging

Conflicts:
	app/views/upload_file_select.js