Adding H_shift_cyclopentadiene to the list of kinetic families.

Adding it to the list of UNIMOLECULAR_KINETICS_FAMILIES

Also adding the reverse template which requires swapping of atomlabels.

This reaction family is important for finding the reactions that lead
towards PAHs.  See the RMG-Java commit here for more details:
https://github.com/GreenGroup/RMG-Java/commit/b130d5b230a97ea07beb1d6115cafd77665c2d21