Add workaround to pin pip to 18.0

The default recipe does not work with the latest version of pip. The
workaround is to override to 18.0

Change-Id: If245c3c51930beba151ed8a42cec15131ea28098
(cherry picked from commit 97af7feec5)

recipes/default.rb

@@ -18,6 +18,13 @@
 # limitations under the License.
 #
 
+# install a python
+python_runtime '2' do
+  provider :system
+  # Workaround for https://github.com/poise/poise-python/issues/133
+  pip_version '18.0'
+end
+
 platform_options = node['openstack']['common']['platform']
 case node['platform_family']
 when 'debian'