remove unused requires of async

services/document-updater/app/coffee/HistoryManager.coffee

@@ -1,7 +1,6 @@
 settings = require "settings-sharelatex"
 request  = require "request"
 logger = require "logger-sharelatex"
-async = require "async"
 HistoryRedisManager = require "./HistoryRedisManager"
 
 module.exports = HistoryManager =

services/document-updater/app/coffee/HistoryRedisManager.coffee

@@ -1,7 +1,6 @@
 Settings = require('settings-sharelatex')
 rclient = require("redis-sharelatex").createClient(Settings.redis.history)
 Keys = Settings.redis.history.key_schema
-async = require "async"
 logger = require('logger-sharelatex')
 
 module.exports = HistoryRedisManager =

services/document-updater/app/coffee/RedisManager.coffee

@@ -1,5 +1,4 @@
 Settings = require('settings-sharelatex')
-async = require('async')
 rclient = require("redis-sharelatex").createClient(Settings.redis.documentupdater)
 _ = require('underscore')
 logger = require('logger-sharelatex')

services/document-updater/app/coffee/ShareJsUpdateManager.coffee

@@ -1,6 +1,5 @@
 ShareJsModel = require "./sharejs/server/model"
 ShareJsDB = require "./ShareJsDB"
-async = require "async"
 logger = require "logger-sharelatex"
 Settings = require('settings-sharelatex')
 Keys = require "./UpdateKeys"