[misc] drop unused async

Signed-off-by: Jakob Ackermann <das7pad@outlook.com>

libraries/redis-wrapper/index.coffee

@@ -1,5 +1,4 @@
 _ = require("underscore")
-async = require "async"
 os = require('os')
 crypto = require('crypto')
 

libraries/redis-wrapper/package.json

@@ -6,7 +6,6 @@
   "author": "ShareLaTeX",
   "license": "ISC",
   "dependencies": {
-    "async": "^2.5.0",
     "coffee-script": "1.8.0",
     "ioredis": "~4.17.3",
     "underscore": "1.7.0"