added enable_grouping option to disable grouping features, enabled by default

spec/summary_spec.rb

@@ -67,4 +67,14 @@ describe Redistat::Summary do
     summary["visitors/us"].should == "4"
   end
   
+  it "should not store key group summaries when option is disabled" do
+    stats = {"views" => 3, "visitors/eu" => 2, "visitors/us" => 4}
+    Redistat::Summary.update_all(@key, stats, :hour, nil, false)
+    summary = db.hgetall(@key.to_s(:hour))
+    summary.should have(3).items
+    summary["views"].should == "3"
+    summary["visitors/eu"].should == "2"
+    summary["visitors/us"].should == "4"
+  end
+  
 end