Bug 518121 - Support multiple terminal connectors with identical label

In case multiple terminal launcher delegates are registered with
identical label, the ID of a delegate is used as fallback instead
of the label in order to disambiguate.

This doesn't look pretty in the UI but it works and it's a generic
solution for an atypical problem.

Change-Id: I4028e1819f7405c2cb65eacf4e84f437900d884e
Signed-off-by: Martin Oberhuber <mober.at+eclipse@gmail.com>