[libsocialcache] Fix a bug in duplicate request handling

Previously, we only handled duplicate requests in the case where
the request was currently running.  This commit ensures that we also
handle it properly in the case where the request is still queued.
It also adds some more verbose debugging output.
Merge pull request #45 from chriadam/duprequest

[libsocialcache] Fix a bug in duplicate request handling
Bump version
[libsocialcache] Added unread field to FB notification database