ZF-2003: Zend_Validate_Date to support more formats than YYYY-MM-DD

Description

Zend_Validate_Date currently requires an input format of YYYY-MM-DD, such as 2007-03-17. In the spirit of flexibility, the validation class should accept various other formats. Further, it should make use of Zend_Date, for DRYer code.

Priority minor since it is trivial to preformat a date such that it follows the YYYY-MM-DD format.

Comments

Can add that it would be nice to be able to pass an array as the value in the same manner as an array can be passed to the Zend_Date-constructor because in my application I got the values from three different form-fields and having to make a string out of those before validating was weird and not very handy when used with the Zend_Filter_Input-object.

In some way it should be able to be easier used with Zend_Filter_Input and different fields as well as other formats of strings as you suggest.

Integrated with SVN-7498