Refactor extract interface DatabaseBuilder from DatabaseConfig

First step in supporting the builder pattern for creating Database

ebean-api/src/main/java/io/ebean/cache/ServerCachePlugin.java

@@ -1,7 +1,7 @@
 package io.ebean.cache;
 
 import io.ebean.BackgroundExecutor;
-import io.ebean.config.DatabaseConfig;
+import io.ebean.DatabaseBuilder;
 
 /**
  * The plugin interface that creates a ServerCacheFactory.
@@ -11,5 +11,5 @@ public interface ServerCachePlugin {
   /**
    * Create the ServerCacheFactory given the server config and background executor service.
    */
-  ServerCacheFactory create(DatabaseConfig config, BackgroundExecutor executor);
+  ServerCacheFactory create(DatabaseBuilder config, BackgroundExecutor executor);
 }