Improved plots in toy_dynamics_tis.ipynb.
Merge remote-tracking branch 'upstream/master' into toy_dynamics

Conflicts:
	examples/ipython/toy_dynamics_tis.ipynb
Removed self.op stuff from Simulator.py.

See https://github.com/choderalab/opentis/issues/63#issuecomment-62557170
and following.
Merge pull request #72 from dwhswenson/toy_dynamics

Toy dynamics: update to ipynb