Added Step for installing python-ceilometerclient

Added a new Step 1 instructing users to start by installing the python-ceilometerclient on the proxy server.

Change-Id: Iaa8b9dcd1c15f83d6588344e53490fa19ce0a24c
backport: icehouse
Closes-Bug: 1360382
Merge "Added Step for installing python-ceilometerclient"