Create compute_mole_sources intermediary since we may want
things in moles and not mass. mass_sources internally calls
this now.
Starting to add derivative version of compute_mole_sources.
Finished up mole_sources deriv routine. mass_sources now
internally calls this.
Merge pull request #6 from pbauman/compute_mole_sources

Add compute_mole_sources, etc. to KineticsEvaluator