Move setting of InstanceManager to WebAppConfiguration to avoid race

Fix up LICENSES.txt
Build.xml cleanup
Debian:
- Add support for with-libtomcat8-java but not with-libjetty9-java for wheezy/jessie
- Fix wheezy/precise/trusty build files to use tomcat8 but not jetty9 packages
- Remove build dependency on ant-optional, not required
- Remove some remaining eclipse-ecj dependencies
- Add short README files for wheezy and jessie

apps/routerconsole/java/src/net/i2p/router/web/WebAppStarter.java

@@ -10,7 +10,6 @@ import net.i2p.router.RouterContext;
 import net.i2p.util.FileUtil;
 import net.i2p.util.SecureDirectory;
 
-import org.apache.tomcat.SimpleInstanceManager;
 import org.eclipse.jetty.server.Handler;
 import org.eclipse.jetty.server.Server;
 import org.eclipse.jetty.server.handler.ContextHandler;
@@ -64,11 +63,6 @@ public class WebAppStarter {
          // and the caller will know it failed
          wac.setThrowUnavailableOnStartupException(true);
          wac.start();
-         // can't do this before start
-         // do we just need one, in the ContextHandlerCollection, or one for each?
-         // http://stackoverflow.com/questions/17529936/issues-while-using-jetty-embedded-to-handle-jsp-jasperexception-unable-to-com
-         // https://github.com/jetty-project/embedded-jetty-jsp/blob/master/src/main/java/org/eclipse/jetty/demo/Main.java
-         wac.getServletContext().setAttribute("org.apache.tomcat.InstanceManager", new SimpleInstanceManager());
     }
 
     /**
@@ -115,7 +109,16 @@ public class WebAppStarter {
 
         // this does the passwords...
         RouterConsoleRunner.initialize(ctx, wac);
+        setWebAppConfiguration(wac);
+        server.addHandler(wac);
+        server.mapContexts();
+        return wac;
+    }
 
+    /**
+     *  @since Jetty 9
+     */
+    static void setWebAppConfiguration(WebAppContext wac) {
         // see WebAppConfiguration for info
         String[] classNames = wac.getConfigurationClasses();
         // In Jetty 9, it doesn't set the defaults if we've already added one, but the
@@ -130,9 +133,6 @@ public class WebAppStarter {
              newClassNames[j] = classNames[j];
         newClassNames[classNames.length] = WebAppConfiguration.class.getName();
         wac.setConfigurationClasses(newClassNames);
-        server.addHandler(wac);
-        server.mapContexts();
-        return wac;
     }
 
     /**