[MSITE-857] Jetty engine fails to resolve web.xml DTD behind corporate proxy

Upgrade web.xml to Servlet 3.1 which Jetty will serve its schema from a bundled
catalog and avoid outbound connections.

Author: michael-o

src/main/resources/run/web.xml

@@ -17,11 +17,11 @@ specific language governing permissions and limitations
 under the License.
 -->
 
-<!DOCTYPE web-app PUBLIC
-    "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
-    "http://java.sun.com/dtd/web-app_2_3.dtd" >
-
-<web-app>
+<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
+         http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
+         version="3.1">
   <filter>
     <filter-name>doxia</filter-name>
     <filter-class>org.apache.maven.plugins.site.run.DoxiaFilter</filter-class>