attempt to fix UKIDSS core: it may be impossible without a complete
shift to requests, so I'm going to revert this set of changes for the
most part...
alfa tests pass on python3.  Cannot test on python2 because of this
bloody error:
ERROR: You appear to be trying to import astropy from within a source
checkout; please run `./setup.py develop` or `./setup.py build_ext
--inplace` first so that extension modules can be compiled and made
importable. [astropy]
MAGPIS fixed - need to use BytesIO, not StringIO, for FITS files
(also, error in previous commit message was b/c there was no compiled
version of astropy when using python setup.py develop)