add forestdb.xml for forestdb repo

Change-Id: I8add47abab0d37015ed7b4ae9a502f1d1fadf879
Reviewed-on: http://review.couchbase.org/34652
Reviewed-by: Sundararaman Sridharan <sundar@couchbase.com>
Tested-by: Sundararaman Sridharan <sundar@couchbase.com>