REF: Results.predict convert to array and adjust shape

Results.predict
convert to ndarray, and check and adjust shape, with unit_tests

closes #1032
supersedes #1178

I tried to let pandas through, but it doesn't help. np.dot for example returns an ndarray.
I left the commented out code for testing DataFrame in the generic tests, but it needs special handling on before return.
I don't know if we have any wrapper code for predict. I didn't see any.