Allow nova client state to create keypairs

- Added a state `keypair_present` that ensures that a keypair with
  a given name is present
- Extended nova/client.sls to call the `keypair_present` state if
  keypairs are defined in metadata

Related PROD: PROD-12876

Change-Id: I928b4e75759069cd0214013688ce82709ad0232e
diff --git a/metadata/service/client/init.yml b/metadata/service/client/init.yml
new file mode 100644
index 0000000..46046d6
--- /dev/null
+++ b/metadata/service/client/init.yml
@@ -0,0 +1,6 @@
+applications:
+  - nova
+parameters:
+  nova:
+    client:
+      enabled: true