adds position and velocity frames for each rigid body manipulator

Conflicts:
	systems/plants/@RigidBodyManipulator/RigidBodyManipulator.m
allow recursive multi-coordinate frames.  add individual robot state frames in (as well as robot position and velocity frames)
fixed some unit tests
fix for atlas state frames
edits from Andres' code review
Merge pull request #342 from RussTedrake/pos_and_vel_frames

Position and velocity frames for RBMs