Move cycle analytics JSON generation to a helper.

1. Use a new format, with each stage having a `title`, `description`,
   and `value.

app/controllers/projects/cycle_analytics_controller.rb

 class Projects::CycleAnalyticsController < Projects::ApplicationController
+  include CycleAnalyticsHelper
+
   before_action :authorize_read_cycle_analytics!
   def show
@@ -6,7 +8,7 @@ class Projects::CycleAnalyticsController < Projects::ApplicationController
     respond_to do |format|
       format.html
-      format.json { render json: @cycle_analytics }
+      format.json { render json: cycle_analytics_json(@cycle_analytics) }
     end
   end

app/helpers/cycle_analytics_helper.rb

+module CycleAnalyticsHelper
+  include ActionView::Helpers::DateHelper
+
+  def cycle_analytics_json(cycle_analytics)
+    cycle_analytics_view_data = [[:issue, "Issue", "Time before an issue gets scheduled"],
+                                 [:plan, "Plan", "Time before an issue starts implementation"],
+                                 [:code, "Code", "Time until first merge request"],
+                                 [:test, "Test", "Total test time for all commits/merges"],
+                                 [:review, "Review", "Time between MR creation and merge/close"],
+                                 [:staging, "Staging", "From MR merge until deploy to production"],
+                                 [:production, "Production", "From issue creation until deploy to production"]]
+
+    stats = cycle_analytics_view_data.reduce({}) do |hash, (stage_method, stage_text, stage_description)|
+      hash[stage_method] = {
+        title: stage_text,
+        description: stage_description,
+        value: distance_of_time_in_words(cycle_analytics.send(stage_method))
+      }
+      hash
+    end
+
+    { stats: stats }
+  end
+end

app/models/cycle_analytics.rb

@@ -6,13 +6,6 @@ class CycleAnalytics
     @from = from
   end
-  def as_json(options = {})
-    {
-      issue: issue, plan: plan, code: code, test: test,
-      review: review, staging: staging, production: production
-    }
-  end
-
   def issue
     calculate_metric!(:issue,
                       TableReferences.issues[:created_at],