Move extensive example to sphinx docs; minor cleanup
Remove unused includes
Rename astropy.vo.samp.core to astropy.vo.samp.utils
Break up astropy.vo.samp into multiple files.

This was discussed and agreed on in GH #972.
In addition to the structure suggested there by @lpaioro,
I put the constants and errors in separate files.
Remove import * in vo.samp ... now imports are fixed for Python 3
Fix docstring parsing error in vo.samp with Python 3
Simplify Python 2 / 3 imports a bit by using the six compat module
Manually convert all vo.samp docstrings from epydoc to numpydoc format
Run autopep8 to clean up all astropy.vo.samp code

cd astropy/vo/samp
autopep8 -i --ignore E501,E126,E128,E225,E226,E231 -r . tests/
Fix import in sampy command line script
minor vo.samp docstring fixes
Format and expand vo.samp documentation
Subclass SAMPProxyError from xmlrpc.Fault
Remove workarounds for Python 2.5 and earlier
Fix imports
More code cleanup, removed more code for Python versions prior to 2.6
Fixed docstring syntax for optional arguments
Docstring cleanup
Disable testing of docs
Removed SAMPLog and use Astropy logging class instead