added new 'shuffle' filter

gives out a different randomized list every time
```
- hosts: localhost
  vars:
    - mylist: [1,2,3,4,5]
  tasks:  
    - debug: msg={{item}}
      with_items: "{{mylist|shuffle}}"
```

in one example:

```
 _________________________ 
< TASK: debug msg={{item}} >
 -------------------------- 
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||
ok: [host1] => (item=4) => {
    "item": 4,                                                                                                                                                             
    "msg": "4"
}
ok: [host1] => (item=3) => {
    "item": 3, 
    "msg": "3"
}
ok: [host1] => (item=2) => {
    "item": 2, 
    "msg": "2"
}
ok: [host1] => (item=1) => {
    "item": 1, 
    "msg": "1"
}
ok: [host1] => (item=5) => {
    "item": 5, 
    "msg": "5"
}
```