Add icon as a opt for notifier

app/assets/javascripts/lib/notify.js.coffee

-# Written by Jacob Schatz @jakecodes
+# Written by GitLab @gitlab
 
 ((w) ->
-  notifyMe = (message,body) ->
+  notifyMe = (message,body, icon) ->
     notification = undefined
     opts = 
       body: body
-      icon: "#{document.location.origin}/assets/gitlab_logo.png"
+      icon: icon
     # Let's check if the browser supports notifications
     if !('Notification' of window)
       # do nothing

app/views/projects/merge_requests/widget/_show.html.haml

@@ -13,6 +13,7 @@
     url_to_automerge_check: "#{merge_check_namespace_project_merge_request_path(@project.namespace, @project, @merge_request)}",
     check_enable: #{@merge_request.unchecked? ? "true" : "false"},
     url_to_ci_check: "#{ci_status_namespace_project_merge_request_path(@project.namespace, @project, @merge_request)}",
+    gitlab_icon: #{asset_path "gitlab_logo.png"},
     ci_enable: #{@project.ci_service ? "true" : "false"}
   };