Rollback and proper bugfix to issue #5

Last commit solved the issue #5 but also changed code related to RMI.
To avoid unoticed bugs, those changes related to RMI were deleted.

This commit only contains bugfix for issue #5
Bugfix Issue #6

SampleAction checks if there's an existing SecurityManager running which
means that there's an active thread listening to the editor.

In case that the user press "start" multiple times, a warning is
displayed.
Merge branch 'testing'

Conflicts:
	src/csaferefactor/actions/SampleAction.java
Roll back (security manager)