[MRM-398] configure guest access by default for pre-configured repositories

Reverted partially r584279. (some good fixes for related bugs in place)
Introduced ArchivaConfiguration.isDefaulted() to aide SecuritySynchronization (startup task in archiva-webapp) to add guest user read-only roles if the configuration was set to default for some reason.

git-svn-id: https://svn.apache.org/repos/asf/maven/archiva/trunk@584903 13f79535-47bb-0310-9956-ffa450edef68

archiva-base/archiva-proxy/src/test/java/org/apache/maven/archiva/proxy/MockConfiguration.java

@@ -97,4 +97,9 @@ public class MockConfiguration
     {
         configListeners.remove( listener );
     }
+
+    public boolean isDefaulted()
+    {
+        return false;
+    }
 }