Add triggers support to behaviors

I started looking into #1642 because I recently needed the functionality.  This was my initial attempt to implement triggers for behaviors without duplicating too much code.  At first glance, this should be BC.  It still needs more specs and the first `calledWith` needs fixed.  I still need to match the expected `args` parameter, but I'm getting max call size.

Need lots of eyes and feedback on this one because behaviors are still relatively new to me too.  It's semi-modeled after the implementation for `behaviorEvents`.

Note this is also introduces `Marionette.buildViewTrigger` and `Marionette.proxyBuildViewTrigger` to avoid code duplication from `View#configureTriggers`, so I'm not sure how we feel about that.
so... I think I'd prefer to ke prefer to keep this version of `behaviorEvents` to the new `BehaviorEventsBuilder` version. I'd like to hear what other people think, but the main reason is that I understand this method and I'm finding it very hard to follow the EventsBuilder code. @jfairbank - I don't think this is a criticism of how you setup EventsBuilder, it is really nicely factored it's just that it's soo generic that it's hard to understand what each thing is doing and how it fits together...