Fixes #7922 - promote uri and http to instance property

This will allow to re-use existing http connection for subsequent
requests.
Fixes #7859 - puppetssh run works on Ruby 1.9+
Bump version to 1.8-develop
Fixes #7922 - promote uri and http to instance property

This will allow to re-use existing http connection for subsequent
requests.
Refs #969 - Proxy-side changes for serving templates from the proxy

An update to @GregSutcliffe's original PR. Ports his original feature to the new
plugin api.