Fix SSL configuration

This is an attempt to augment and extend the SSL features of haproxy on top of the default recipe of haproxy. This adds two site specific attributes to account for these features.

The basic issues that are being fixed in this PR are:

1. Fix backend SSL termination (upstream is broken)
2. Add ability to enable frontend SSL but still use http for the backend
It might be a good idea to add one more test where <code>node['osl-haproxy']['enable_ssl_backend']</code> is set to <code>false</code> and ensure the config at least looks sane.