Add force: true to avoid dirty git repo

add force: true to avoid dirty git repo, which will do a hard reset from
upstream, this is related to you ansible version, if it's not working,
please try this way -> https://goo.gl/2Sg2Eq

Change-Id: I7e21921d0812cb143a2e2c3f794667354791c8db

multi-node-aio/playbooks/deploy-osa.yml

@@ -35,6 +35,7 @@
         repo: https://git.openstack.org/openstack/openstack-ansible
         dest: /opt/openstack-ansible
         version: "{{ osa_branch | default('master') }}"
+        force: true
       when:
         - pre_config_osa | default(true) | bool