Added reduced potential energy to tests re issue #8
Added Nij accumulation for issue #7
Added a harmonic oscillator test.
Cleanup in test.
Added working test of HREX using power oscillators.
Added simple tests for save and load functionality.
Trying to un-break renamed directory structure for easier merge...
Better name for test-nose dir
Working PT and tests.
Rename some tests.
Updated setup.cfg to run doctests, added some basic docstrings.
Updated docstrings to permute function.
Merge pull request #9 from choderalab/new_tests

[WIP] Start adding nose tests