Allow naming of verify test.

Current tests are (anonymous). This patch allows passing test name when
setting up the verify.

```js
exports.verify = verify('beep boop', function (args, t) {
    t.plan(1);
    t.equal(args[0], '555');
});
```

Before

    TAP version 13
    # (anonymous)
    ok 1 should be equal

    1..1
    # tests 1
    # pass  1

    # ok

After

    TAP version 13
    # beep boop
    ok 1 should be equal

    1..1
    # tests 1
    # pass  1

    # ok