Add proxy support to XML-RPC transports.
Add proxy support to XML-RPC transports.

release-engineering/kobo,pombredanne/https-git.fedorahosted.org-git-kobo,pombredanne/https-git.fedorahosted.org-git-kobo,pombredanne/https-git.fedorahosted.org-git-kobo,release-engineering/kobo,release-engineering/kobo,release-engineering/kobo,pombredanne/https-git.fedorahosted.org-git-kobo