Adds explicit channels between FSMs to add in tracing message flows.

* Adds channels between FSMs
* Adds FSMTrace model
* Adds FSMTrace storage and download

Channels between FSMs make the processing pipeline delegation explicit
and allow for better instrumentation to trace the state of the entire
pipeline including FSM state transitions and message flow through
the pipeline.  This feature is not turned on by default and is
only necessary for debugging or certain kinds of testing.

awx/network_ui/models.py

@@ -156,3 +156,15 @@ class ToolboxItem(models.Model):
     toolbox_item_id = models.AutoField(primary_key=True,)
     toolbox = models.ForeignKey('Toolbox',)
     data = models.TextField()
+
+
+class FSMTrace(models.Model):
+
+    fsm_trace_id = models.AutoField(primary_key=True,)
+    fsm_name = models.CharField(max_length=200,)
+    from_state = models.CharField(max_length=200,)
+    to_state = models.CharField(max_length=200,)
+    message_type = models.CharField(max_length=200,)
+    client = models.ForeignKey('Client',)
+    trace_session_id = models.IntegerField(default=0)
+    order = models.IntegerField(default=0)