Fixed proxy registration for foreman_api 0.1.18+
Quote password field.  Otherwise a pass with non-alphanumeric characters
will fail.
Configuration in YAML

This patch moves configuration to /etc/puppet/foreman.yml. By moving the
configuration into a settings file, we can use external_node.rb and
foreman-report.rb as plain files.

This is based on a patch by @frimik.