Allocate application IDs for IOU nodes on the controller.

An application ID is used by IOU to generate its interface Mac addresses. They must be unique across all opened projects sharing the same computes to avoid Mac address collisions.

tests/handlers/api/compute/test_iou.py

@@ -42,7 +42,7 @@ def fake_iou_bin(images_dir):
 @pytest.fixture
 def base_params(tmpdir, fake_iou_bin):
     """Return standard parameters"""
-    return {"name": "PC TEST 1", "path": "iou.bin"}
+    return {"application_id": 42, "name": "PC TEST 1", "path": "iou.bin"}
 
 
 @pytest.fixture