Sanitize keypair name for heat

Engine creates keypair for the stacks it creates. Keypairs are named
after the scenario which can contain version information such as
master, 1.1, and so on.

But OpenStack heat considers keypair names containing dots insecure
so this change replaces dots with underscores if there is any.

Change-Id: I3a50da1c5a2407a1d92c117157c6914895adc39d
diff --git a/playbooks/roles/create-stack/tasks/create-stack.yml b/playbooks/roles/create-stack/tasks/create-stack.yml
index 546fd40..116b90b 100644
--- a/playbooks/roles/create-stack/tasks/create-stack.yml
+++ b/playbooks/roles/create-stack/tasks/create-stack.yml
@@ -19,7 +19,7 @@
 
 - name: Set keypair name
   set_fact:
-    keypair_name: "keypair-{{ stack_name }}"
+    keypair_name: "keypair-{{ stack_name | regex_replace('\\.', '_') }}"
 
 - name: Delete keypair '{{ keypair_name }}'
   os_keypair: