Make WebOb version specification more flexible

Change the WebOb version to >=1.0.8 as a temporary
measure to allow the actual version update to 1.2.3
to roll out across the projects one at a time without
breaking the integration tests.

Change-Id: Ia4f9f92ae7013098706924eef8728bcd85869c29
Signed-off-by: Doug Hellmann <doug.hellmann@dreamhost.com>