Set required and verification rule during creating ReCaptchaField

[sallyx]

Fix for issue #9

[f3l1x]

Well, thank you, but it's not really fix.

You said that you've already tried $form->addRecaptcha()->setRequired(TRUE)->setMessage('Are you bot?'); It's same code in your PR.

[sallyx]

Yes, the last example works. This PR fixes first 3 issues and calls setRequired() automatically, which improves fourth issue too.

[f3l1x]

Oh, oukey. I will use your code a follow my codestyle. Thank you.