added n_atoms and n_bonds checks to monolayer kwarg test
added n_atoms and n_bonds checks to monolayer kwarg test

tcmoore3/mbuild,Jonestj1/mbuild,tcmoore3/mbuild,summeraz/mbuild,sallai/mbuild,ctk3b/mbuild,iModels/mbuild,sallai/mbuild,Jonestj1/mbuild,iModels/mbuild,ctk3b/mbuild,summeraz/mbuild