[fix] remove host key checks for ansible

Until we figure out a way to add host keys to the config without
trouble, disable host key checking when calling ansible.

Not doing so could result in blocked calls, as ansible was asking
questions during the run.

chi-appliance.py

@@ -172,7 +172,7 @@ def do_configure(argv):
                 '        state: present\n'
                 '        generate_ssh_key: yes\n'
                 '    - name: Execute ansible on frontend\n'
-                '      shell: '
+                '      shell: ANSIBLE_HOST_KEY_CHECKING=False'
                 ' ansible-playbook -i inventory.yaml ' + playpath + '\n'
                 '      args:\n'
                 '        chdir: ~/ansible\n'