Installation guide updated

While testing the Icehouse release on a RHEL6 system with Python 2.6 installed,
the backslash character present in the endpoint examples was being reproduced in the endpoint.
fixed by using %() instead of \$().

Change-Id: I634dd979a6f7de231d4bf8cbe7c5376dc70f1be2
Closes-Bug: #1324195
Merge "Installation guide updated"