Added 'containsNumbers' validator

This validator checks that an input text string has a certain number of numbers/integers present.  For instance, if min=2 and max=4 then the the string "ab12xy" and "abc1234xyz" are valid but not "ab1zy".  Default messages are present. Useful for adding basic password complexity requirements. 
Hi @01000101 
I think this should return ``false``
for example if you have ``min = 4`` and the ``value = 'x12'`` then the validator will return ``true`` and make the field valid, absurd!