Add "filePrefix" parameter to play.PropertiesConfLoader

to ease migration from Play1 projects.

Modify "multi-module-app" test to work from "conf/" directory:
- use "conf/application.conf" for configuration
- use "conf/routes" for routes

This is an advanced setup, so play.server.Starter couldn't help.

While at it, fix README about Criminals example project.

Ref: replay-framework#198

README.md

@@ -217,7 +217,7 @@ The following list breaks down the porting effort into tasks:
 * Port the dependency specification from `conf/dependencies.yml` (Ivy2 format) to `build.gradle` (Gradle format).
 * Ensure that `app/play.plugins` file (or the file where the `play.plugins.descriptor` configuration property is pointing) is on the classpath (e.g. `sourceSets.main.resources { srcDir 'app' }`) and add all plugins you need explicitly (see the section on "Plugins").
 * Add the `app/<appname>/Application.java` and `app/<appname>/Module.java` (see the
-[RePlay example project](/Users/andrei/projects/replay/replay-tests/criminals) for inspiration). 
+[RePlay example project](replay-tests/criminals/) and [multi-module-app test](replay-tests/multi-module-app/) for inspiration).
 * Play1's [`PropertiesEnhancer`](https://github.com/playframework/play1/blob/master/framework/src/play/classloading/enhancers/PropertiesEnhancer.java) was removed.
   * This enhancer reduces the boilerplate needed to make classes adhere to the "Java Bean" standard.
   In short: a *bean* is a Java class that (1) implements `java.io.Serializable`, (2) implements public getter/setter methods for accessing the state, and

framework/src/play/PropertiesConfLoader.java

@@ -17,13 +17,25 @@ public class PropertiesConfLoader implements ConfLoader {
   private final Pattern overrideKeyPattern = Pattern.compile("^%([a-zA-Z0-9_\\-]+)\\.(.*)$");
   private final Pattern envVarInterpolationPattern = Pattern.compile("\\$\\{([^}]+)}");
 
+  private String filePrefix = "";
+
+  public PropertiesConfLoader() {
+    this("");
+  }
+
+  public PropertiesConfLoader(String filePrefix) {
+    if (filePrefix != null) {
+      this.filePrefix = filePrefix;
+    }
+  }
+
   public static Properties read(String playId) {
     return new PropertiesConfLoader().readConfiguration(playId);
   }
 
   @Override
   public Properties readConfiguration(String playId) {
-    return readOneConfigurationFile(playId, "application.conf");
+    return readOneConfigurationFile(playId, filePrefix + "application.conf");
   }
 
   public Properties readOneConfigurationFile(String playId, String filename) {
@@ -114,7 +126,7 @@ private void resolveIncludes(Properties propsFromFile, String playId, String inh
     for (Map.Entry<Object, Object> e : propsFromFile.entrySet()) {
       if (e.getKey().toString().startsWith("@include.")) {
         try {
-          String filenameToInclude = e.getValue().toString();
+          String filenameToInclude = filePrefix + e.getValue().toString();
           propsFromFile.putAll(readOneConfigurationFile(filenameToInclude, playId, inheritedId, confs));
         }
         catch (Exception ex) {

replay-tests/multi-module-app/app/app/hello/HelloWorldApp.java

@@ -1,10 +1,20 @@
 package hello;
 
+import play.ClasspathResource;
+import play.Play;
+import play.PropertiesConfLoader;
+import play.inject.DefaultBeanSource;
+import play.mvc.CookieSessionStore;
 import play.server.Starter;
 
 public class HelloWorldApp {
   public int start(String playId) {
-    return Starter.start(playId);
+    Play play = new Play(new PropertiesConfLoader("conf/"), new DefaultBeanSource(), new CookieSessionStore());
+    play.minimalInit(playId);
+    Play.routes = ClasspathResource.file("conf/routes");
+    Play.pluginCollection.loadPlugins();
+    play.start();
+    return Starter.start(play);
   }
   public static void main(String[] args) {
     new HelloWorldApp().start(System.getProperty("play.id", "prod"));