Use const instead of let

Use property shorthand

[NEW] Show info about multiple instances at admin page

Close #6646

* ESLint add rule `object-shorthand`

* ESLint rocketchat-livechat/assets/rocket-livechat.js

* Add ecmascript package to all packages

* Use ecmascript package for server and client on saml package

* Fix compilation

* Add eslit rule `one-var`

* ESLint add rule `no-var`

* Add ecmascript package to all packages

* Use ecmascript package for server and client on saml package

* Fix compilation

Just admins can change a Default Channel to Private (the channel will be a non default channel) (#6426)

* change ChatRoom to AdminChatRoom on channelSettingsDefault

* just admin can change the type of a default channel, and even been an admin you must confirm this

Closes #5806

* Change all instances of Meteor.Collection for Mongo.Collection
http://stackoverflow.com/questions/25756664/is-it-mongo-collection-or-meteor-collection

* Include api.use(‘mongo’) where it was missing

* Allow uploads to Google Cloud Storage

* Use the uniqueID instead of the hostname for uploads to google storage

* Fix admin combobox selection

Closes #5652

Closes #5620 #5538