Add explicit hydrogens to forgotten entry in thermo library CH.py

Copied from Beat's commit https://github.com/GreenGroup/RMG-database/commit/0761f5357fd97c2e9a1dd437d41dd4c1bea3083e
Get rid of history comparisons and writing of history in import scripts.
Create a temporary importOldPyDatabase.py script for converting to new adjlist.