Update app.coffee to work with Metrics v2

services/track-changes/app.coffee

@@ -1,3 +1,5 @@
+Metrics = require "metrics-sharelatex"
+Metrics.initialize("track-changes")
 Settings = require "settings-sharelatex"
 logger = require "logger-sharelatex"
 TrackChangesLogger = logger.initialize("track-changes").logger
@@ -23,8 +25,7 @@ TrackChangesLogger.addSerializers {
 }
 
 Path = require "path"
-Metrics = require "metrics-sharelatex"
-Metrics.initialize("track-changes")
+
 Metrics.memory.monitor(logger)
 
 child_process = require "child_process"
@@ -35,6 +36,8 @@ app = express()
 
 app.use Metrics.http.monitor(logger)
 
+Metrics.injectMetricsRoute(app)
+
 app.post "/project/:project_id/doc/:doc_id/flush", HttpController.flushDoc
 
 app.get "/project/:project_id/doc/:doc_id/diff", HttpController.getDiff