Comparison between quantities and plain numbers is inconsistent and unsafe

If I have a quantity with a unit, e.g.,

     t = 50 * pq.ms

then 

    t > 1

returns `True` whereas

    t.simplified > 1

returns `False`. Arguably, both should raise a ValueError just like

    t - 1

does in this example.

If the community agrees, I would be happy to prepare a pull request to change the behavior.