Add ability to syndicate galleries

Currently post syndication simply copies post content to the remote
site.
That makes [gallery] short code to contain wrong image IDs.
This patch parses post content, fetches all galleries and upload images
to the remote site prior to the syndication. It adjusts gallery code
with new IDs and then syndication continues normally.
Merge Duplicate remote site removal bug (pull req 40)
Merged branches

Merged in custom field syndication
Merge pull request #41 from andreybrokeit/Gallery-Shortcode-Syndication

Add ability to syndicate galleries