Don't access the net while building docs

(Note this hasn't been submitted upstream)

Change-Id: I42c6e3a5062db209a0abe00cebc04d383c79cbcb
(cherry picked from commit f2b4bb4e45afcc178200966193a7b87401c534d7)
remove deprecated assert_unicode sqlalchemy attribute

Removing this enables use with sqlalchemy 0.8.0
The deprecation is described upstream at:
http://docs.sqlalchemy.org/en/latest/changelog/changelog_08.html#change-ad44af79c886d1bb283042deb64f9cbe

Change-Id: Ia34b38245c6abe1ddb4162eee89459a7130deacb