Introduce an ansible_version dict as runner variable

  Given the version:
    "1.6 (ansible_version_var 14499e8bf3) last updated 2014/03/21 17:07:50 (GMT +200)"

  We get the special variable:
    "ansible_version": {
        "full": "1.6",
        "major": 1,
        "minor": 6,
        "revision": 0,
        "string": "1.6 (ansible_version_var 14499e8bf3) last updated 2014/03/21 17:07:50 (GMT +200)"
       }

  modified:   lib/ansible/runner/__init__.py

also in plain bin/ansible:
$ ansible -m debug -a var=ansible_version all
localhost | success >> {
    "ansible_version": {
        "full": "1.6", 
        "major": 1, 
        "minor": 6, 
        "revision": 0, 
        "string": "1.6 (ansible_version_var 69ee37f7a0) last updated 2014/03/21 18:12:46 (GMT +200)"
    }
}