Added extra tests for two state checks.
Added extra tests for two state checks.

jchodera/pymbar,choderalab/pymbar,mrshirts/pymbar,wesbarnett/pymbar,mrshirts/pymbar,kyleabeauchamp/pymbar,jchodera/pymbar,jchodera/pymbar,Lnaden/pymbar,mrshirts/pymbar,Lnaden/pymbar,Lnaden/pymbar,wesbarnett/pymbar,wesbarnett/pymbar,kyleabeauchamp/pymbar,jchodera/pymbar,wesbarnett/pymbar,choderalab/pymbar,kyleabeauchamp/pymbar,choderalab/pymbar,mrshirts/pymbar,kyleabeauchamp/pymbar