Add a "remote_submit" role

[ccnifo]

This PR defines a new type of node : remote_submit

The idea comes from this DESY talk, slide 11: a remote submit allows you to:

• let your users login
• provide them a configured condor_submit to submit jobs to a schedd, mentioned in conf (may be a personnal conf, ~/.condor/user_config, see this doc)
• be able to get this host down (for software updates for example) seamlessly, so no downtime when a breach in the kernel has to be patched
• retrieve your files if you have a shared FS between schedd and remote_submit

So this PR implements a fourth type of node (after manager, scheduler,worker), called remote_submit (I'm interested if you have a better name to suggest!)
It has no running service and few configuration files, just enough to be able to authenticate a user so that he can pass condor_submit and condor_q.

[kreczko]

Thanks, that looks good!