VOL-376 : Fix for Null Pointer Exception when subscriber is not provisioned
Patchet contains
1. Fix for Null Pointer Exception when subscriber is not provisioned in Sadis
2. README.md updates for Sadis configuration of subscriber and device
3. Correcting log levels of some of the logs

Change-Id: I59270faff77d05013a4313629c60911148533e19
diff --git a/src/main/java/org/opencord/aaa/AaaManager.java b/src/main/java/org/opencord/aaa/AaaManager.java
index 2f885db..1df4574 100755
--- a/src/main/java/org/opencord/aaa/AaaManager.java
+++ b/src/main/java/org/opencord/aaa/AaaManager.java
@@ -423,6 +423,9 @@
                             subsService.get(nasPortId);
                     if (subscriber != null) {
                         stateMachine = new StateMachine(sessionId, subscriber.cTag());
+                    } else {
+                        log.error("Could not create new state machine for {}", nasPortId);
+                        return;
                     }
                 } else {
                     stateMachine = new StateMachine(sessionId, VlanId.vlanId((short) 0));