Release octavia-lib 2.0.0 for Ussuri

We are bumping the major version to 2.0.0 to signify the end of
python 2.x support in the library.

Change-Id: If9b80cb8bb4893fd9d640b229df3fb54132aac0b

deliverables/ussuri/octavia-lib.yaml

@@ -1,4 +1,7 @@
 ---
+branches:
+  - location: 2.0.0
+    name: stable/ussuri
 include-pypi-link: true
 storyboard: openstack/octavia-lib
 release-model: cycle-with-intermediary
@@ -12,3 +15,7 @@ releases:
     projects:
       - repo: openstack/octavia-lib
         hash: 12d678a04943aea6c1987ce098c2ff4659109137
+  - version: 2.0.0
+    projects:
+      - repo: openstack/octavia-lib
+        hash: 99118d2e47f24fc9aeccb8da530cd8133e530cc9