Merge branch 'downsample-duration' into 'master'

Downsample duration sum (to calculate total consuming time)

See merge request !6

queries/grape/grape_transaction_timings_per_action.txt

 CREATE CONTINUOUS QUERY grape_transaction_timings_per_action ON $DATABASE
 BEGIN
-    SELECT mean("duration") AS duration_mean,
+    SELECT sum("duration") AS duration_sum, 
+        mean("duration") AS duration_mean,
         percentile("duration", 95) AS duration_95th,
         percentile("duration", 99) AS duration_99th,
         mean(sql_duration) AS sql_duration_mean,

queries/rails/rails_transaction_timings_per_action.txt

 CREATE CONTINUOUS QUERY rails_transaction_timings_per_action ON $DATABASE
 BEGIN
-    SELECT mean("duration") AS duration_mean,
+    SELECT sum("duration") AS duration_sum,
+        mean("duration") AS duration_mean,
         percentile("duration", 95) AS duration_95th,
         percentile("duration", 99) AS duration_99th,
         mean(sql_duration) AS sql_duration_mean,