Create and use ansible.cfg for engine

ansible.cfg lets us configure various options such as ssh and others
and it makes sense to ship this together with engine rather than
asking users to modify ~/.ssh/config files or configure Jenkins slaves
in advance.

Created ansible.cfg file is taken from kubespray as it already ships
its own ansible.cfg.

By default, Ansible looks at various places for ansible.cfg so we place
engine ansible.cfg into root of engine repo and run all the playbooks
from there. It also helps us to get rid of StrictHostKeyChecking by
moving it to ansible.cfg.

Created ansible.cfg is only used for engine itself as other tools might
come with their own ansible.cfg as it can be seen for kubespray.

Change-Id: Ida201e0815858401f5adc23cc0936e23c6edaf87
diff --git a/ansible.cfg b/ansible.cfg
new file mode 100644
index 0000000..8082630
--- /dev/null
+++ b/ansible.cfg
@@ -0,0 +1,8 @@
+[ssh_connection]
+ssh_args = -o ControlMaster=auto -o ControlPersist=60m -o ConnectionAttempts=100 -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no
+[defaults]
+host_key_checking=False
+deprecation_warnings=False
+inventory_ignore_extensions = ~, .orig, .bak, .ini, .cfg, .retry, .pyc, .pyo, .creds
+[inventory]
+ignore_patterns = artifacts, credentials