feat(ui-date-mask): include timezone offset in matching regex

* refactor(ui-date-mask): regex should match timezone offset

it should match
0000-00-00T00:00:00.000Z
0000-00-00T00:00:00.000+00:00

* docs: updated demo to include ui-date-mask

demo/index.html

@@ -155,6 +155,11 @@ <h2>ui-br-car-plate-mask</h2>
 		<input type="text" name="field25" ng-model="carPlate" ui-br-car-plate-mask><br>
 		<span></span>Plate: <span ng-bind="carPlate"></span> - <span ng-bind="form.field25.$error | json"></span><br>
 		<br>
+
+		<h2>ui-date-mask</h2>
+		<input type="text" name="field26" ng-model="initializedDateMask" ui-date-mask><br>
+		<span></span>Date: <span ng-bind="initializedDateMask"></span> - <span ng-bind="form.field26.$error | json"></span><br>
+		<br>
 	</form>
 </body>
 </html>

src/global/date/date.js

@@ -4,7 +4,7 @@ var moment = require('moment');
 var StringMask = require('string-mask');
 
 function isISODateString(date) {
-	return /^[0-9]{4}-[0-9]{2}-[0-9]{2}T[0-9]{2}:[0-9]{2}:[0-9]{2}\.[0-9]{3}Z$/
+	return /^[0-9]{4}-[0-9]{2}-[0-9]{2}T[0-9]{2}:[0-9]{2}:[0-9]{2}\.[0-9]{3}([-+][0-9]{2}:[0-9]{2}|Z)$/
 		.test(date.toString());
 }