UX: improvements to new dashboard

- remove inactive user report and replace with posts
- clean up internals so grouping by week happens on client
- when switching periods old report was not destroyed leading to bugs
- calculate trend based on previous interval ... not previous 30 days
- show percentages for mau/dau
- be more careful about utc date usage
- show uniqu and click through rate on search panel
- publish key of report with report so we only load the correct one
- subscribe earlier in channel in case of concurrency issues

config/locales/client.en.yml

@@ -2748,6 +2748,7 @@ en:
         activity_metrics: Activity Metrics
 
         reports:
+          trend_title: "%{percent} change. Currently %{current}, was %{prev} in previous period."
           today: "Today"
           yesterday: "Yesterday"
           last_7_days: "Last 7 Days"

config/locales/server.en.yml

@@ -880,6 +880,7 @@ en:
       title: "Posts"
       xaxis: "Day"
       yaxis: "Number of new posts"
+      description: "New posts created during this period"
     likes:
       title: "Likes"
       xaxis: "Day"
@@ -914,7 +915,7 @@ en:
       labels:
         term: Term
         searches: Searches
-        unique: Unique
+        click_through: Click Through Rate
     emails:
       title: "Emails Sent"
       xaxis: "Day"