Fix  python3.x compatibility for stable 2.0 branch

Change-Id: I958d02873e4ba76be72230365dff8e500fa31b3c
Signed-off-by: George Keishing <gkeishin@in.ibm.com>
diff --git a/lib/gen_robot_plug_in.py b/lib/gen_robot_plug_in.py
index 5c1dd06..cfcb660 100755
--- a/lib/gen_robot_plug_in.py
+++ b/lib/gen_robot_plug_in.py
@@ -8,7 +8,11 @@
 import sys
 import subprocess
 from robot.libraries.BuiltIn import BuiltIn
-import commands
+try:
+    import commands
+except ImportError:
+    import subprocess
+
 import os
 import tempfile