#779 Strip EXIF data as user preference

My solution for issue #779 including 
- Strip EXIF data from uploaded images.
- Privacy user preference to allow not striping.
- DB migration for new user pref.
- Testing both cases.

I need a review of photo_spec file.

Included image from [Flickr](https://www.flickr.com/photos/fscholz/13919459137/in/photostream/)