Rename Meteor.Collection -> Mongo.Collection
Rename Mongo.Collection.Cursor -> Mongo.Cursor, Mongo.Collection.ObjectID -> Mongo.ObjectID
Fix docs and self-test
Revert "Rename Meteor.Collection -> Mongo.Collection"

This reverts commit 96952dda2b8b2bd5df8cf4556ebd8da2a535203a.

Conflicts:
	packages/ddp/livedata_tests.js
	packages/minimongo/minimongo.js
	packages/mongo/collection.js
	packages/mongo/mongo_driver.js
	packages/mongo/mongo_livedata_tests.js
	packages/mongo/oplog_tests.js
	packages/reactive-dict/reactive-dict.js
	packages/session/session_tests.js
	tools/auth.js
Rename Meteor.Collection to Mongo.Collection again
Add backcompat
Add link redirect
Add Mongo export
Run jsdoc
Rename Meteor.Collection -> Mongo

Summary:
Meteor.Collection -> Mongo.Collection
Meteor.Collection.ObjectID -> Mongo.ObjectID
Meteor.Collection.Cursor -> Mongo.Cursor

Test Plan:
meteor test-packages
meteor self-test

Reviewers: avital, dgreenspan

Reviewed By: dgreenspan

CC: emily, dgreenspan

Differential Revision: https://phabricator.meteor.com/D796