introduce pip_install_gr

This creates a new pip_install_gr that installs from global
requirements allowed versions. Now that stable branches are getting
capped all of devstack needs to be fixed to do things like this.

Change-Id: I8fd0ef2bfc544ca2576fab09d3018f760b8848fe
diff --git a/lib/keystone b/lib/keystone
index 7b41812..31659f4 100644
--- a/lib/keystone
+++ b/lib/keystone
@@ -524,7 +524,7 @@
         setup_dev_lib "keystonemiddleware"
     else
         # When not installing from repo, keystonemiddleware is still needed...
-        pip_install keystonemiddleware
+        pip_install_gr keystonemiddleware
     fi
 }