Fix charges and lone pairs for Helium in fromAdjacencyList() and updateCharge().

Also made calculating charges no longer redundent since it is done in updateCharge().
Special inchi handling for both H and He.
Add a Helium unit test.
Merge pull request #273 from connie/master

Fix handling of Helium in RMG-Py. Looks good to me, and passes Travis tests.