Comparison between quantities containing NumPy Arrays now yield and array

Before this change:

    >>> np.ones(3) * ureg.meter == np.ones(3) * ureg.meter
    True

Now the output is consistent with numpy:

    >>> np.ones(3) * ureg.meter == np.ones(3) * ureg.meter
    array([ True,  True,  True], dtype=bool)

BACKWARDS INCOMPATIBLE CHANGE

Close #75