py.Complex is missing __str__ and __repr__

[raff]

Printing a complex number displays the py.Complex type instead of the real+imag values:

>>> print(3+1j)
<complex64 instance at %!p(py.Complex=(3+1i))>

[ncw]

THis is all done now - thanks @raff

PS Next time put Fixes #31 in the commit message and it will auto close the issue :-)