Add the `server_proxy_scheme` parameter to configure the scheme used for
the proxy server. This completes the configuration parameters for the
proxy server.
Stop passing all the "rhsm_", and "server_" module arguments to
"Rhsm.register()", and thus as arguments for
"subscription-manager register":
- right before calling "Rhsm.register()", "Rhsm.configure()" is called
to configure subscription-manager with all the "rhsm_", and "server_"
arguments; hence, they are already configured
- the passed argument to "--serverurl" is partially wrong:
"Rhsm.register()" passes only the hostname, whereas the other bits
(port and prefix) are supported too; this "works" because port and
prefix were already configured previously, and the lax parsing that
subscription-manager does allows for missing bits
- the parsing done by subscription-manager for "--baseurl" strips out
the URL scheme and always uses https: this means that specifying
"rhsm_baseurl: http://server" as module parameter will be taken as
"https://server" by subscription-manager; since "rhsm_baseurl" is
already configured by "Rhsm.configure()", this issue is gone
