Revert "test: added -D option to subunitrun"

This reverts commit ac0bba2ea1.

"python -m subunit.run" is the preferred way of running tests to
generate subunit. I also don't want to move too far away from
the standard test running infrastructure for python so that
other test runners (nosetests, trial, tribunal, ...) can be used with
Samba code.

source4/scripting/bin/subunitrun

@@ -56,8 +56,6 @@ credopts = options.CredentialsOptions(parser)
 sambaopts = options.SambaOptions(parser)
 parser.add_option_group(credopts)
 parser.add_option_group(sambaopts)
-parser.add_option('-D', '--directory', dest='directory', default=None,
-                  help='set test directory')
 try:
     from subunit.run import TestProgram
 except ImportError:
@@ -74,8 +72,5 @@ samba.tests.cmdline_credentials = credopts.get_credentials(lp)
 if getattr(opts, "listtests", False):
     args.insert(0, "--list")
 
-if opts.directory:
-    sys.path.append(opts.directory)
-
 runner = SubunitTestRunner()
 program = TestProgram(module=None, argv=[sys.argv[0]] + args, testRunner=runner)