Changed implementation of proxy setup

Changed the setup_http_proxy method to setup_proxy.
The same arguments are used as before. This change includes
workarounds for pulp proxy configuration. However, until BZ1114083
is fixed, easier proxy support will not be possible.
I have no preference at all as my editor highlight the `{[n]}`. I've commented because the consistency as I think consistency > personal preference.

We can leave this as is and refactor others in order to have consistency and readability.