Add button to remove terminated commands for long-running process console

See http://forum.springsource.org/showthread.php?135631-GGTS-3-2-Consoles-not-terminating-with-Grails-2-2-1

That thread mentions 'stop button' which is fixed now https://issuetracker.springsource.com/browse/STS-3259
But it also mentions the 'X' buttons that appear on Process consoles.

It would be nice to also implement equivalents for the long running process command consoles.