Add test_kinetics_checkChildParentRelationship databaseTest

Implemented parent/child checking for nodes. I changed the way
matchNodeToChild in base.py worked:

-For the case where the parent is a LogicOr, it simply checks if the child
is in the components of the LogicOr

-There is also the interesting case where we have intermediate LogicOr
nodes e.g:

L3: GroupA
  L4: LogicOr
    L5: GroupB

In this case, we also need to check that GroupB is subgroup of GroupA. I
have implemented some extra lines for this in
test_kinetics_checkChildParentRelationship.

Also, we must ignore a check between the L4 LogicOr and L3 GroupA because
there is actually nothing to check. This was added to matchNodeToChild
to automatically pass this case.

I'm not convinced that we should have intermediate LogicOr groups like
this, but I've left the flexibility to do so for now.

Finally, I also changed the name of the function matchtoLogicOr to just
matchLogicOr as I thought it sounded more concise.
Modified getMcGowanVolume method to include sulfur.

This method is used when calculating diffusivities in liquid phase. I
removed all the other unused elements, too.
Conflicts:
	rmgpy/data/solvation.py
Adds saveEntry() method for solvation database.

Writes string representation of solute or solvent information.
Fixes some old ambiguities in the solvation database.

The solvation database encompasses both solute and solvent
data. Also, we have a solute library that is now used.
Use the default families for liquid-phase example.

I don't know if this is correct or not, but it doesn't work with all the families.
Merge pull request https://github.com/GreenGroup/RMG-Py/pull/236 'bslakman-solvation-fixes'
Clean up print statements when loading kinetic depositories.
Save the recommended.py list of families when saving RMG-database.
Add functions for saving the transport and solvation databases.

Currently saveEntry for solvation is still NotImplemented
Make aromatic unit tests a bit more descriptive.
Clean up print statements in unit tests.

Conflicts resolved:
	rmgpy/data/solvationTest.py
	rmgpy/molecule/groupTest.py