Use tarball for python-reddwarfclient dependency

* Openstack-ci creates a tarball at tarballs.o.o when tag matches:
  ref: ^refs/tags/([0-9]+\.)+[0-9]*
        (alpha|beta|candidate|rc|a|b|c|r|g)[0-9]*$

Fixes bug#1131509

Change-Id: I5e3d00c57dfe977f6e9a01dea25b97c8fcdf0d1d

tools/test-requires

@@ -10,7 +10,7 @@ pylint
 webtest
 wsgi_intercept
 proboscis
-python-reddwarfclient==0.1.2
+http://tarballs.openstack.org/python-reddwarfclient/python-reddwarfclient-0.1.2.tar.gz#egg=python-reddwarfclient
 mock
 mox
 testtools>=0.9.22