Fix line in nosetests.1 being treated as man directive

This is actually a bug in Docutils, but here we work it around
until it is properly fixed.
Use Sphinx manpage writer instead of Docutils one

And update Makefile accordingly.
Remove docinfo from man.rst, not needed with Sphinx builder
Regenerate the man page
Merge pull request #642 from mitya57/manpage-formatting

Add manpage building support to conf.py, and fix formatting errors
Remove manpage and manbuilder in favor of Sphinx's man page builder.