-Cube_and_Cuboid to Geometries. Same as Stick_and_Ball
-Added "shape" parameter to Boundary geometry so that user can pick "spheres" or "cubes"
-Added open_air_diffusivity to test_script. Creates network that has porosity = 100%, checks that effective diffusivity is equal to bulk diffusivity.
-Changed the faces to boundaries on another test. (still fails that test)