Programatic control over versions controller to return

- If no version is specified the default controller is used. For now this is v1 and can change in the future. Therefore
 -- http://hostname:9101/v1/actions and http://hostname:9101/actions are the same url.

```
$ http http://localhost:9101/v1/triggers
HTTP/1.1 200 OK
Access-Control-Allow-Headers: Content-Type,Authorization,X-Auth-Token
Access-Control-Allow-Methods: GET,POST,PUT,DELETE,OPTIONS
Access-Control-Allow-Origin: http://localhost:3000
Access-Control-Expose-Headers: Content-Type,X-Limit,X-Total-Count
Connection: keep-alive
Content-Length: 205
Content-Type: application/json; charset=UTF-8
Date: Fri, 12 Dec 2014 01:00:30 GMT

[
    {
        "id": "548a2ceb0640fd34b443647b",
        "name": "st2.generic.actiontrigger",
        "pack": "core",
        "parameters": {},
        "type": "core.st2.generic.actiontrigger"
    }
]

$ http http://localhost:9101/triggers
HTTP/1.1 200 OK
Access-Control-Allow-Headers: Content-Type,Authorization,X-Auth-Token
Access-Control-Allow-Methods: GET,POST,PUT,DELETE,OPTIONS
Access-Control-Allow-Origin: http://localhost:3000
Access-Control-Expose-Headers: Content-Type,X-Limit,X-Total-Count
Connection: keep-alive
Content-Length: 205
Content-Type: application/json; charset=UTF-8
Date: Fri, 12 Dec 2014 01:00:39 GMT

[
    {
        "id": "548a2ceb0640fd34b443647b",
        "name": "st2.generic.actiontrigger",
        "pack": "core",
        "parameters": {},
        "type": "core.st2.generic.actiontrigger"
    }
]
```