Update README.rst with Django version requirement and how to make a secret key.
Cope with ValueErrors from invalid SMILES strings.

This is needed for the new RDkit branch of RMG-Py
Escape SMILES in URLs to avoid C#C problems.

Closes #55
Added a view for /database/kinetics/families/H_Abstraction/TS_groups/

This shows the group additive values for transition state geometry estimation.
Fix to handle the empty TS uncertainty.