Install test-requirements for swiftclient functional tests

The functional test for python-swiftclient currently fails all the time because
an required package for testing (testrepository) is missing.

swift itself uses nosetest to start functional tests, but python-swiftclient
uses testr and thus requires the package testrepository to be installed.

This patch simply installs all requirements for the tests. I was able to
reproduce this error localy using a fresh virtualenv environment, and this
patch fixed it for me.

Change-Id: I5417f74d324b1915155e321c3a87138069aa35fa

jenkins/jobs/swift.yaml

@@ -67,6 +67,7 @@
 
           function post_test_hook {{
               cd /opt/stack/new/python-swiftclient
+              sudo pip install -r test-requirements.txt
               # Launch V2 auth tests and v1 tests after.
               timeout -s 9 ${{FUNCTEST_TIMEOUT}}m bash .functests --verbosity=3 && \
                   SWIFT_TEST_CONFIG_FILE=/opt/stack/new/swift/test/sample.conf \