Move all Etherpad's access control from Meteor to a separated [Node application](https://github.com/bigbluebutton/bbb-pads).
This new app uses [Etherpad's API](https://etherpad.org/doc/v1.8.4/#index_overview)
to create groups and manage session tokens for users to access them. Each group
represents one distinct pad at the html5 client.
- Removed locked users' access to pads: replaced readOnly pad's access with a new pad's content sharing routine
- Pad's access is now controlled by [Etherpad's API](https://etherpad.org/doc/v1.8.4/#index_overview)
- Closed captions edited content now reflects at it's live feedback
- Improved closed caption's dictation mode live feedback
- Moved all Etherpad's API control from Meteor to a separated [app](https://github.com/bigbluebutton/bbb-pads)
- Included access control both in akka-apps and bbb-pads
Remove padIds from the closed captions MongoDB collection subscription.
Users now have to fetch the padId from Meteor when needed. Meteor is
responsible for checking the user's access level and return the
proper id.
Associate pads with meetings so session validation is restricted to the
meeting's valid session tokens.
Meteor will dispatch new redis events on shared notes and closed captions
pads creation. This event will go through apps and reach web to populate
a new meeting's pad collection that contains all valid pad id's for that
session. Nginx will use this collection to check if the user's session token
belongs to the pad's authorized users.
Besides these modifications, an extra change will be needed at notes.nginx.
Location /pad/p/ needs to change it's auth_request:
from /bigbluebutton/connection/checkAuthorization;
to /bigbluebutton/connection/validatePad;
