make Settings.parallelSqlQueryLimit a config setting

app/coffee/DbQueue.coffee

@@ -1,13 +1,14 @@
 async = require "async"
+Settings = require "settings-sharelatex"
 
 queue = async.queue((task, cb)->
 		console.log("running task")
 		task(cb)
-	, 1)
+	, Settings.parallelSqlQueryLimit)
 
 queue.drain = ()->
     console.log('HI all items have been processed')
-    
+
 module.exports = 
 	queue: queue