new feature; enable revid in permalink


git-svn-id: http://svn.wikimedia.org/svnroot/pywikipedia/branches/rewrite@11024 6a7f98fc-eeb0-4dc1-a6e2-c2c589a08aa6
Merge remote-tracking branch 'git-svn'

Conflicts:
	pywikibot/page.py