Revert "Comment out kinetics library generation for now."

Trying to turn this on again. Not sure why it was disabled...

This reverts commit 445832201b31a737afd5455b30544273e45c77eb.
Don't crash if you can't save the .kinetics.py file
Added 'THERM' as a string in initialization of thermo.txt file.
Mechanism 487-Schenk starts thermo.txt with 'THERM'