Protect contentious transactions with a semaphore

The create_port and delete_port request generates
highly contentious transactions to (de)allocate
an unique IP addresses updating a single table.
Exclusive Locks work better than transactions to
handle concurrency here.
Add v2013.1.2.mido6 in RPM packaging
Merge pull request #49 from davecahill/stable/grizzly

Protect contentious transactions with a semaphore