Support PAC proxies.

What a horrible wart lingering from the early days of the Internet. Note to
future designers: please do not express configuration using a Turing complete
language.

Thanks jenriq for getting the ball rolling on this.

Closes #196.

core/src/main/java/com/threerings/getdown/data/Application.java

@@ -822,8 +822,7 @@ public class Application
      * Returns a URL from which the specified path can be fetched. Our application base URL is
      * properly versioned and combined with the supplied path.
      */
-    public URL getRemoteURL (String path)
-        throws MalformedURLException
+    public URL getRemoteURL (String path) throws MalformedURLException
     {
         return new URL(_vappbase, encodePath(path));
     }