Initial support of capsule settings

The capsule module serves as entry point for proxy/pulp node configuration (we
don't use the proxy module directly as we need to make sure the certs are set
properly).

This patch adds support for setting the proxy on the same machine as the
master. By default, the puppet and puppetca gets configured. Other features
can be added using `--capsule-*` configurations.

By default, it also registers the proxy into Foreman.

Also the README is update to reflect the latest changes. I've removed the
node-certs-generate and node-install stuff, as the recent changes in Katello
and the installer itself probably broke this feature, so for now, only
installing all-in-one should be working.

Therefore, also the `node-certs-generate` and `node-install` scripts are
disabled.