Assuming bash? #131

When I spin up a shell from the pod menu, I get the error:

sh: bash: not found

This makes sense since not every container contains bash. In fact, a huge portion does not (e.g. alpine). The mechanism still works in that it falls back on the existing sh shell, but this has confused several people using the extension on our team. It would be nice if there were a way to glean or at least configure the shell expectation for launching a pod terminal.