shell command only opens an ssh session if VM is on a bridged network

[belgaied2]

The shell command is limited to VMs with bridged networking. It should also support getting a shell on VMs that are on the pod network.
It might be interesting to check how kubectl exec command works.

[belgaied2]

After checking out the kubectl exec command, I figured it might not be the best way. However, since I am already using a wrapper around the system's ssh command as of #10, it made more sense to check out the kubectl port-forward command implementation.

And, it works!

Now, the shell command will:

• intelligently find out if the VM has any bridged network interface, and if not, it will look for a Pod Network interface
• if a bridge network interface exists, it will be used by default, but this can be overiden using the flag --pod-network (boolean flag, it exists or it doesn't)
• if no bridge network exists, but a pod network interface exists, then the program will open a port forward to the pod driving the VM, by using a high number local port as a source, then it will use ssh to connect to localhost on that high number port. Exiting the SSH session automatically closes the port forward session.
• if no bridged network and no pod network interfaces exist, an error will be thrown.

Closing this as of 0efc7f5