Feature: LDAP refactoring (#16950)

* incapsulates multipleldap logic under one module

* abstracts users upsert and get logic

* changes some of the text error messages and import sort sequence

* heavily refactors the LDAP module – LDAP module now only deals with LDAP related behaviour

* integrates affected auth_proxy module and their tests

* refactoring of the auth_proxy logic

vendor/github.com/robfig/cron/README.md

@@ -1,4 +1,4 @@
-[![GoDoc](http://godoc.org/github.com/robfig/cron?status.png)](http://godoc.org/github.com/robfig/cron) 
+[![GoDoc](http://godoc.org/github.com/robfig/cron?status.png)](http://godoc.org/github.com/robfig/cron)
 [![Build Status](https://travis-ci.org/robfig/cron.svg?branch=master)](https://travis-ci.org/robfig/cron)
 
 # cron

vendor/github.com/robfig/cron/doc.go

@@ -84,7 +84,7 @@ You may use one of several pre-defined schedules in place of a cron expression.
 
 Intervals
 
-You may also schedule a job to execute at fixed intervals, starting at the time it's added 
+You may also schedule a job to execute at fixed intervals, starting at the time it's added
 or cron is run. This is supported by formatting the cron spec like this:
 
     @every <duration>