Ensure python is installed

devstack can call python before parsing the
package requirements, so the python installation
needs to be done eralier.

Closes-Bug: #1488625
Change-Id: I85cca899aeedd741cf7dc695435d61390e260f22

Author: afazekas

stack.sh

@@ -335,6 +335,10 @@ if [ -z "`grep ^127.0.0.1 /etc/hosts | grep $LOCAL_HOSTNAME`" ]; then
     sudo sed -i "s/\(^127.0.0.1.*\)/\1 $LOCAL_HOSTNAME/" /etc/hosts
 fi
 
+# Ensure python is installed
+# --------------------------
+is_package_installed python || install_package python
+
 
 # Configure Logging
 # -----------------