Allow specification of release title in release command

Right now, @rultor release command will create a release whose title is the same as the ticket description. Most of the time this doesn't make any sense.

For instance, the title of release 1.61.9 is "Rultor down again", because it was released from #1097 which had the same title:

It would have been more appropriate to call it something like, "Fixed Rultor memory issues". I propose that we be able to add an optional title to the release command:

@rultor release, tag=`0.61.9`, title=`Fixed Rultor memory issues`

Specifying the title would make Rultor use said title, otherwise it will default to the current behavior.