[BUGFIX] Unregistered validator options

The validators CaptchaValidator and UniqueValidator
use unregistered options which leads to exceptions
in TYPO3 CMS 6.2.

The defaults for supported options are now set to:
* CaptchaValidator(type=srfreecap)
* UniqueValidator(global=1)

Resolves: #60140
Change-Id: I33e251077151653c3c516fc5960c6b80088ad648
Reviewed-on: https://review.typo3.org/31439
Reviewed-by: Sebastian Fischer
Tested-by: Sebastian Fischer