TST: Add numexpr arithmetic tests.

Only add 'div' if not python 3

Also checks dtype in test cases for series
ENH: Allow evaluate to pass kwargs to numexpr
BUG: Fix __truediv__ numexpr error

by passing truediv=True to evaluate for __truediv__
and truediv=False for __div__.
BUG: Remove broken frame mod and floordiv str_rep

`%` (modulus) intermittently causes floating point exceptions when used with
numexpr.

`//` (floordiv) is inconsistent between unaccelerated and accelerated
when dividing by zero (unaccelerated produces 0.0000, accelerated
produces `inf`)
TST: Make test_expressions cover more arithmetic operators