Support to enable VOLTHA in cord-tester.
VOLTHA can now be started by cord-tester by specifying voltha_loc in manifest file.
voltha_intf specifies the interface for voltha to listen.
A sample manifest-voltha.json can be modified accordingly before starting cord-tester.
Changed the default olt_type to simulated_olt in volthaTest configuration json.
This would enable testing of voltha tests.
Fix indentation broken in voltha tests earlier.

Change-Id: Ia18b870c83dcb60c15c07f8602579494f32457c9
diff --git a/src/test/voltha/volthaTest.json b/src/test/voltha/volthaTest.json
index 8ad1319..d397700 100644
--- a/src/test/voltha/volthaTest.json
+++ b/src/test/voltha/volthaTest.json
@@ -1,5 +1,5 @@
 {
-    "OLT_TYPE" : "tibit_olt",
+    "OLT_TYPE" : "simulated_olt",
     "OLT_MAC"  : "00:0c:e2:31:12:00",
     "VOLTHA_HOST" : "172.17.0.1",
     "VOLTHA_REST_PORT" : 8881