Splitting Validate_* packages into separate git repositories

Aside from sharing a common namespace, the classes in 
https://github.com/pear/Validate are independent and packaged separately 
(separate package.xml files).

I propose these be split into separate git repositories. Most other 
validate packages are split already:
https://github.com/pear/repositories?page=15

Splitting into separate repos will make it easier to find things (I was 
lookinf for Validate_Finance_CreditCard and couldn't find it). Splitting 
into separate repos will also make adding PHP Composer support easier.

Cheers,
Mike