Manage version string with versioneer

This entailed building the docs from setup.py rather than 'make'.
Deprecate copy_from() and copy_to()

The methods copy_from() and copy_to() of the Cursor object are deprecated
because it's simpler and more flexible to use the execute() method with
a fileobj parameter.
Add note on client encoding to the quickstart page
Added info about mailing list
Add support for two-phase commit DBAPI extension

Thanks to Mariano Reingart's TPC code on the Google Code version:

https://code.google.com/p/pg8000/source/detail?r=c8609701b348b1812c418e2c77bb1ec272e6f29c

on which the code for this commit is based.
Prepare for new release