[TECHNICAL-SUPPORT] LPS-43148 Logo Editor (image_uploader) generates FileExtensionException

Hey Julio,

Sorry for the misleading comment yesterday... :-( I forgot the fact that the "previewURL" comes from an instance variable not from the form directly, so updating the "previewURL" hidden field of the form is fine.

Edification

Never check pulls/codes from mobile without seeing the whole picture (code context). :-)

##### Note

As I can see, you fixed-up some of my commits. Thus, I amended the commit messages in two cases
- lipusz@d06739b & lipusz@8472999

Thanks!