Add database invariant checker []

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=119162082

java/com/google/domain/registry/util/FormattingLogger.java

@@ -19,6 +19,7 @@ import static java.util.Arrays.asList;
 import com.google.common.base.Predicate;
 import com.google.common.collect.FluentIterable;
 
+import java.util.logging.Handler;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
@@ -102,4 +103,12 @@ public class FormattingLogger {
   public void severefmt(Throwable cause, String fmt, Object... args) {
     log(Level.SEVERE, cause, String.format(fmt, args));
   }
+
+  public void addHandler(Handler handler) {
+    logger.addHandler(handler);
+  }
+
+  public void removeHandler(Handler handler) {
+    logger.removeHandler(handler);
+  }
 }