Add .gitignore based on https://github.com/github/gitignore/blob/master/Qt.gitignore with some extra Symbian/Tweetian files
Add sis files to .gitignore
Add Harmattan build file 'tweetian' to .gitignore
Add https://secure.flickr.com/photos/{user-id}/{photo-id} as a valid Flickr image URL and remove hardcoding of URL lengths
Add imgur.com for image previews