Return the uuid of the executed primitive

Return the uuid of the queued primitive from ExecutePrimitive, the first
step in allowing the orchestrator check the status and output of the primitive.

Signed-off-by: Adam Israel <adam.israel@canonical.com>
diff --git a/n2vc/vnf.py b/n2vc/vnf.py
index 7244b22..899e407 100644
--- a/n2vc/vnf.py
+++ b/n2vc/vnf.py
@@ -373,6 +373,12 @@
                 raise
 
     async def ExecutePrimitive(self, model_name, application_name, primitive, callback, *callback_args, **params):
+        """
+        Queue the execution of a primitive
+
+        returns the UUID of the executed primitive
+        """
+        uuid = None
         try:
             if not self.authenticated:
                 await self.login()
@@ -392,11 +398,12 @@
                     if unit:
                         self.log.debug("Executing primitive {}".format(primitive))
                         action = await unit.run_action(primitive, **params)
-                        # action = await action.wait()
+                        uuid = action.id
                 await model.disconnect()
         except Exception as e:
             self.log.debug("Caught exception while executing primitive: {}".format(e))
             raise e
+        return uuid
 
     async def RemoveCharms(self, model_name, application_name, callback=None, *callback_args):
         try: