Handle image deletion in "_images/temporary" folder

[hermanTenuki]

For now, if image is deleted on server in "_images/temporary/" folder, but user still have it opened, settings will no more work and all will be frozen without any errors displaying. This looks not right.
(Images are auto-deleting in 24-25 hours after upload).

[hermanTenuki]

Due #32 , _temporary_images/ is now in _images/temporary/.

[hermanTenuki]

Issue is fixed in #62, but when an image is re-uploading, Apply button is no longer in loading animation and it looks like nothing is happening at the moment. Need to make this animation go on before it's uploading is done.

[hermanTenuki]

Also it needs to use provided art settings