Move mos9.0-proposal repo to new class

https://github.com/Mirantis/mk-lab-salt-model/pull/194
diff --git a/linux/system/repo/mos9_latest.yml b/linux/system/repo/mos9_latest.yml
new file mode 100644
index 0000000..a55c8ae
--- /dev/null
+++ b/linux/system/repo/mos9_latest.yml
@@ -0,0 +1,18 @@
+parameters:
+  linux:
+    system:
+      package:
+        python-msgpack:
+          version: latest
+      repo:
+      # This repository is needed because the python-influxdb package
+      # required for Mitaka Ceilometer is only present in
+      # mos9.0-proposed from the 9.0-latest repository
+        mirantis_latest_openstack_proposed:
+          source: "deb http://mirror.fuel-infra.org/mos-repos/ubuntu/snapshots/9.0-latest/ mos9.0-proposed main"
+          architectures: amd64
+          key_url: "http://mirror.fuel-infra.org/mos-repos/ubuntu/snapshots/9.0-latest/archive-mos9.0.key"
+          pin:
+            - pin: "release a=mos9.0-proposed"
+              priority: 400
+              package: "*"