Fixes #2722 - Support for crossdomain auth

Newest Signo support authentication across more domains. We just need to
look not only to a cookie but parse parameters for getting username.
fixes #2724 - use __method__ instead of static method names in SSO
fixes #2645 - non-admin users can now create smart variables
Fixes #2712 - Handle Net::SSH::Disconnect gracefully
part of a fix to #2716 error in discovery plugin menu and user without provisioning permissions
the other part is a fix to the discovery plugin.
fixes 2707 - host save fails for non-admin if host has a BMC interface