Edits to Thermo estimation unit tests.

1) removed a bug causing an error,
2) split the aromatic species into a separate set of tests.

The non-aromatic tests all pass EXCEPT for cyclopenta-1,3-diene
C1C=CC=C1 which seems to be giving different thermo now.
I am not sure why, or where the original "correct" numbers came from.
Have our ring corrections changed?

The aromatic tests fail because we read in the species via a SMILES string
and in the process Kekulize them. Probably if we specified them via adjacency
lists we would do OK, but for now I will leave these as failing tests until we
properly fix aromaticity detection.