add greetest/mysubprocess.py that backports Popen.kill() method

greentest/mysubprocess.py

+import sys
+import subprocess
+from subprocess import *
+
+class Popen(subprocess.Popen):
+
+    if not hasattr(subprocess.Popen, 'kill'):
+
+        def kill(self):
+            try:
+                from os import kill
+                sys.stderr.write('Sending signal 9 to %s\n' % self.pid)
+                kill(self.pid, 9)
+            except ImportError:
+                sys.stderr.write('Cannot kill on this platform. Please kill %s\n' % self.pid)
+