wait_for module: Allow search_regex to be used with port

It is possible that someone may want to look for a string in a port connection with `wait_for` to validate that things are indeed ready and not just open.

For example the following could verify that "OpenSSH" is in the response on port 22:

```
$ ansible all -i localhost, -c local -m wait_for -a 'host=test.example.org port=22 search_regex=SSH'

localhost | success >> {
    "changed": false,
    "elapsed": 1,
    "path": null,
    "port": 22,
    "search_regex": "OpenSSH",
    "state": "started"
}
```