Corrected adjlists for USC-Mech-ii

The changeTripletToSinglet method in rmgpy/molecule/molecule was used for the singlet radical cases. The method  changes the multiplicity to 1, but the adjlist still reports the atom as having 2 unpaired electrons (instead of a lone pair and an empty shell). I can't remember if this is what we want or if this should have been corrected.

Should address #50.