Implement a "ho ssh" command for accessing arbitrary delegate/role

[smithfarm]

Right now it is unnecessarily difficult to ssh to a given node (i.e. delegate-role). First you have to run ho probe delegates or use AWS Web Console to determine the public IP address, and then you to have to install a separate package ("susecon-automation-client") and run the ssh-to-node command to actually SSH to the node.

This could be made much easier by implementing a ho ssh command that would take --delegate and --role options. Or just positional arguments, since delegate is numeric and role is presumably alphanumeric.