Use pypi for python-swiftclient dependency.

Using github as a package source is less reliable in the Jenkins test
framework than using pypi. This is because the Jenkins test framework
has a local pypi mirror.

Change-Id: Ia904d39ce70f5c2bd7d6edb9172f8226131074e2
Make rebalance take a seed
(cherry picked from commit 9ee14f43190366e7a463c22e044ea98ac52ed1aa)