SSH connection plugin creates ControlPersist socket files in a secure directory

Files were being created in /tmp, but will now be created in $HOME/.ansible/cp/
Addresses CVE-2013-4259: ansible uses a socket with predictable filename in /tmp
Place retry file in the user's home dir instead of /var/lib/tmp

Addresses CVE-2013-4260: predictable filename used for failed results
in world writable directory.
Commenting out default ssh arguments line in ansible.cfg

Also removing the ControlPath option, as it will now be auto-generated
if the ControlPersist option is set in the arguments.