Added explaination comment on averaged kinetics

Better explains for kinetics why we use geometric means for A
and arithmetic means for everything else.
Added explaination comment on averaged kinetics

Better explains for kinetics why we use geometric means for A
and arithmetic means for everything else.
Don't fail output html if nasa polynomial can't be evaluated at 298K.
Merge branch 'master' of github.com:GreenGroup/RMG-Py