Added support for selecting ajax request method.
Added support for selecting ajax request method.

Backwards compatibility: Default is "GET", which is the default in
jQuery, so it should be backwards compatible.

Example: Add this attribute to any form field that has an ajax
validator: `data-validation-ajax-type="post"`.

Testing: I have not added any new tests, since there are no tests for
ajax validators yet.

ReactiveRaven/jqBootstrapValidation