Add RemoteIpValve

As the Tomcat instance created by this buildpack is always located
behind a proxy, this change adds the RemoteIpValve to the Tomcat
configuration.  This change ensures that functionality such as
HttpServletRequest.isSecure() works properly in the Cloud Foundry
environment.

[#52956737, #8]

resources/tomcat/conf/server.xml

@@ -27,14 +27,17 @@
 
   <Service name="Catalina">
 
-    <Connector port="${http.port}" protocol="HTTP/1.1"
-               connectionTimeout="20000" bindOnInit="false"/>
+    <Connector port="${http.port}" protocol="HTTP/1.1" connectionTimeout="20000" bindOnInit="false"/>
 
     <Engine name="Catalina" defaultHost="localhost">
 
-      <Host name="localhost"  appBase="webapps"
-            unpackWARs="true" autoDeploy="true">
+      <Valve className="org.apache.catalina.valves.RemoteIpValve" protocolHeader="x-forwarded-proto"/>
+
+      <Host name="localhost"  appBase="webapps"unpackWARs="true" autoDeploy="true">
       </Host>
+
     </Engine>
+
   </Service>
-</Server>
+
+</Server>