Analytical jacobian and rate derivative.
Change rate derivative function to return an array derivative for all reactions
Perform direct local sensitivity calculation within dassl solver if turned on

Should be adaptable for additional reaction systems other than the
isothermal/isobaric system SimpleReactor.  Each new reaction system will need
an analytical jacobian and rate derivative function.
Move thermo database unittest out of deprecated unittest folder.
Merge branch 'master' of git://github.com/jwallen/RMG-Py
Merge branch 'jacobian'
Merge branch 'master' of git://github.com/jwallen/RMG-Py
Don't restrict duplicate reactions only to reactions of the same family.

Was previously causing errors when loading chemkin files when duplicate
reactions are not the same family.
Fixed missing import of Reaction class in rmgpy.pdep.network.

Ironically this error was only occurring when about to raise a different
exception.