More cleanup for scale test.
Re-use the code from vsg test and add interfaces in vsg test case to be usable from scale tests.

Change-Id: I7213151d5186ee2f5f96733fe1a0231d63c4391c
diff --git a/src/test/scale/__init__.py b/src/test/scale/__init__.py
index ec5e91b..3d1e823 100644
--- a/src/test/scale/__init__.py
+++ b/src/test/scale/__init__.py
@@ -21,6 +21,7 @@
 subscriber_dir = os.path.join(working_dir, '../subscriber')
 tls_dir = os.path.join(working_dir, '../tls')
 vrouter_dir = os.path.join(working_dir, '../vrouter')
+vsg_dir = os.path.join(working_dir, '../vsg')
 __path__.append(utils_dir)
 __path__.append(fsm_dir)
 __path__.append(subscriber_dir)
@@ -28,3 +29,4 @@
 __path__.append(cli_dir)
 __path__.append(tls_dir)
 __path__.append(vrouter_dir)
+__path__.append(vsg_dir)