Tor man page fixes

Hi Nick, I'm adding Stem integ test coverage for tor's man page. In particular it tests that...

• We can make a validly formatted man page.
• Lots of assertions on its content.
• Checks that the man page matches tor's actual config options, giving a nice reminder when adding to tor that we also need to update the manual.

In doing this naturally ran into a handful of minor issues with our present man page. See the man_page_fixes branch of my repository for the improvements...

https://gitweb.torproject.org/user/atagar/tor.git/log/?h=man_page_fixes