AWS Region as a mandatory field

public/app/plugins/datasource/cloudwatch/partials/config.html

@@ -20,7 +20,7 @@
 					Default Region<tip>Specify the region, such as for US West (Oregon) use ` us-west-2 ` as the region.</tip>
 				</li>
 				<li>
-					<input type="text" class="tight-form-input input-large last" ng-model='current.jsonData.defaultRegion' placeholder=""></input>
+					<input type="text" class="tight-form-input input-large last" ng-model='current.jsonData.defaultRegion' placeholder="region name" required></input>
 				</li>
 			</ul>
 			<div class="clearfix"></div>