First draft of GasSolidCatalyticWall

This class is designed to deal with gas-solid reactions
at the wall of the form, e.g. N + C(s) -> CN
Start building GasSolidCatalyticWall
Set up unit testing for GasSolidCatalyticWall
Adding bc parsing for GasSolidCatalyticWall

Added initial pass at implementation of parsing for the
GasSolidCatalyticWall. Needs testing.
Only supports unit stochiometry at the moment.
Simple accessor for CatalyticWallBase pointers

It's convenient for an application to have access to this, but
it should be generalized to handle the case for multiple
pointers per boundary id. It's good enough for now though.
Bug fix for GasSolidCatalyticWall parsing

Application now runs correctly using this new boundary class.
Added regression test for GasSolidCatalyticWall

Just took existing constant (gas_recombination) catalytic wall
test and added a gas_solid_catalytic_wall on the other side of the
tube. Had to adjust air_4sp.xml to not have the ridiculous CN
dissociation reaction which makes no physical sense.
Merge pull request #88 from pbauman/gas_solid_catalytic_wall

GasSolidCatalyticWall