Added New Feature #3258 - Variable Material Property Names in chemical_reactions module

We wanted to allow multiple species diffusivities in porous media, which was not allowed (or was difficult) with the old implementation where material property names were fixed in the code ("diffusivity," "porosity," etc.). We have changed this to allow the user to specify diffusivities and such in the input file, so the same kernels can be used in the same porous media mesh with multiple diffusing and dissolving species.