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.  

This is a bit simpler ... does it work (maybe after adjusting the tolerance)?
```
assert_allclose(table3['aperture_sum'], true_flux)
```