No effective change - add a test for saveAll() with existing batch mode on

Assert that it does not flush the batch.  We want the batch to continue and flush normally.

src/test/java/org/ebeantest/LoggedSqlCollector.java

@@ -52,6 +52,10 @@ public class LoggedSqlCollector {
     return basicAppender.collectEnd();
   }
 
+  public static List<String> current() {
+    return basicAppender.collectContinue();
+  }
+
   private static class BasicAppender extends UnsynchronizedAppenderBase<ILoggingEvent> {
 
     List<String> messages = new ArrayList<>();
@@ -85,5 +89,14 @@ public class LoggedSqlCollector {
       return tempMessages;
     }
 
+    /**
+     * Return the collected SQL and continue.
+     */
+    List<String> collectContinue() {
+      List<String> tempMessages = messages;
+      messages = new ArrayList<>();
+      return tempMessages;
+    }
+
   }
 }