DRY
Define MO::Basis::LCAO#nuclear_attraction
Define AO::Gaussian::Contracted#nuclear_attraction
Define AO::Gaussian::Primitive#nuclear_attraction
Define PimitiveProduct#nuclear_attraction_integral
Remove an unappropriate spec
MO::Basis#core_hamiltonian should all be finite
Use rspec 2.14.0.rc1

Fixed bug(?) in be_within().percent_of()