Changing aperture photometry output to return astropy.table

This is the first draft for returning the photometry results in an ``astropy.table``.
I think the main question is what we want to return. Only flux, fluxerr, or something more, e.g. positions, or even the apertures (as metadata), etc.  

Oops, my memory is apparently not that good. Only the previous one was fixed previously in an ugly commit, so fix all of these in the latest commit in this branch.