roles/strongswan: Base role for strongSwan setup

The *strongwan* role is intended to be used as a dependency of other
roles that use strongSwan for IPsec configuration. It deploys some basic
configuration and configures the *strongswan* service, but does not
configure any connections, secrets, etc.

roles/strongswan/handlers/main.yml

@@ -0,0 +1,4 @@
+- name: restart strongswan
+  service:
+    name=strongswan
+    state=restarted