Bump version
[libsocialcache] Provide API to allow purging Posts

This commit adds the removePosts(int accountId) function to the
posts database interface.  This allows clients to purge the local
database of posts for a given account.
Merge pull request #13 from chriadam/purge

[libsocialcache] Provide API to allow purging Posts
[libsocialcache] Purge cached image files correctly

Previously, the cleanup routine was called without executing the
query to determine which images files needed to be purged.
Merge pull request #14 from chriadam/purgeImages

[libsocialcache] Purge cached image files correctly
Bump version
[libsocialcache] Improve locking and database cleanup

This commit adds more locking around sensitive code areas, and also
ensures that each derived type is responsible for closing the database
at the appropriate time (depending on the threading being used).
Merge pull request #15 from chriadam/lock

[libsocialcache] Improve locking and database cleanup
Bump version