Actor type montoring

Issue #89 

This pr emulates the failure case, where an Actor is created via the japi.Creator interface and has no visible type during runtime. It provides a treatment of the case, and an associated test suite.

In addition, since the current assumption is that only implementations of that interface which return a 'generic' Actor class leave the actor type inaccessible during runtime, this pr also updates sampling and actor count so that we sample and count actors 'per type'. We *still* apply path filters (for sampling) to any cases this doesn't catch, and still record their actor count; however, we will count all remaining generic/anonymous actors as being of one type. 

ActorCellMonitoringAspect is now final, because the reference hash maps it contains are non-static. This may implement a serious misunderstanding, and should be considered a potential bug.

If the number of untyped actors in a monitored system is generally non-zero, this indicates that there is another creation point for such generic actors we're still not catching, or actors we're catching that we shouldn't, and should be reported as a bug (or that there are 'race conditions' or other weirdness in the execution code and pointcut logic isn't enough, in which case it should be reported as a very difficult bug).

The failing TravisCI test 'CountFilteredActorCellMonitoringAspectSpec' is succeeding on one of my machines (iMac + OSX) but failing on my other (Thinkpad + Ubuntu), so I do have some traction on it now. May be the vdb...