update .gitignore file
Modify imports, make them explicit relative imports.  Cleanup namespace in Cache.py.
Modify imports, make them explicit relative imports.  Cleanup namespace in catalog.py.
Cleanup namespace in graphtab.py.
Cleanup namespace in locations.py.
PEP8 fixes. Make imports explicit relative imports. Cleanup namespace in obsbandpass.py.
Turn off Python 3.x testing for now.

PEP8 fixes. Make imports explicit relative imports.

 Cleanup namespace in observation.py.
Make all imports explicit relative imports.  Clean up namespace.
Make all imports explicit relative imports.  Clean up namespace in reddening.py.
Make all imports explicit relative imports.  Clean up namespace in refs.py.
Make all imports explicit relative imports.  Clean up namespace in renorm.py.
Make all imports explicit relative imports.  Clean up namespace in reseltable.py.
Make all imports explicit relative imports.  Clean up namespace in spectrum.py.
Make all imports explicit relative imports.  Clean up namespace in spparser.py.
Clean up namespace in tables.py.
Change imports in units.py to be relative explicity imports.  Define a Vega class in spectrum.py.
Changed pyfits to astropy.io.fits. Minor PEP8 fixes at some places.
sypysyn subpackage is now a separate repo as per spacetelescope/stsynphot#1
Renamed package name to synphot, so that it will be astropy.synphot when merged into astropy. Reorganized codes to how astropy is organized, so that transition from affiliated package to sub-package is easier. Renamed pysynexcept module to synexceptions for clarity. Disabled test_simple.py because any test will not work until codes are completely refactored (ongoing work in a different branch).
Refactored the pysynphot portion that is going to astropy. Wrote unit tests.