Use pip 7 for ironic

pip8 cannot install the ironic requirements due to
https://github.com/pypa/pip/issues/3384.

Change-Id: Ic0c70baca83b91cb55ddf4f787c4ff25aaefc062

elements/ironic-agent/install.d/ironic-agent-source-install/60-ironic-agent-install

@@ -11,7 +11,8 @@ SCRIPTDIR=$(dirname $0)
 # Install the latest version of pip and setuptools which has some
 # fixes for building behind proxy.
 curl -o /tmp/get-pip.py https://bootstrap.pypa.io/get-pip.py
-python /tmp/get-pip.py
+#python /tmp/get-pip.py
+pip install pip==7.1.2
 rm -f /tmp/get-pip.py
 pip install -U setuptools