Create blank.js

Added blank validator to support dynamic validation messages returning after a server call. This validator provides a placeholder when bootstrapValidator modifies the DOM for validation messages.

Closes #542

src/js/validator/blank.js

@@ -0,0 +1,30 @@
+(function ($) {
+
+    $.fn.bootstrapValidator.validators.blank = {
+        /**
+         * placeholder validator that can be used to display a custom validation message 
+         * returned from the server
+         * Example:
+         *
+         * (0) a "blank" validator is applied to an input field.
+         * (1) data is entered via the UI that is unable to be validated client-side.  
+         * (2) server returns a 400 with JSON data that contains the field that failed 
+         *     validation and an associated message.
+         * (3) ajax 400 call handler does the following:
+         *
+         *      bv.updateMessage(field, 'blank', errorMessage);
+         *      bv.updateStatus(field, 'INVALID');
+         *
+         * @param {BootstrapValidator} validator The validator plugin instance
+         * @param {jQuery} $field Field element
+         * @param {Object} options Can consist of the following keys:
+         * - message: The invalid message
+         * @returns {Boolean}
+         */
+
+        validate: function (validator, $field, options) {
+            return true;
+        }
+    };
+
+}(window.jQuery));