Add ssh functionality

It might still need some polish and a proper unit test.

example.tcl
-----------
shell "localhost"

ssh "machine"
if {[execute hostname] == "machine"} {
    result OK "Connecting to $host"
}

config.yaml
-----------
machine:
    SSH_IP: 10.0.0.1
    SSH_PORT: 1234
    PROMPT: "@machine"

Signed-off-by: Richard A (rical) <ric41@yahoo.se>