FRE-600: Fix code review blockers

- Consolidated duplicate UndoManagers to single instance
- Fixed connection promise to only resolve on 'connected' status
- Fixed WebSocketProvider import (WebsocketProvider)
- Added proper doc.destroy() cleanup
- Renamed isPresenceInitialized property to avoid conflict

Co-Authored-By: Paperclip <noreply@paperclip.ing>

node_modules/xtend/README.md

@@ -0,0 +1,32 @@
+# xtend
+
+[![browser support][3]][4]
+
+[![locked](http://badges.github.io/stability-badges/dist/locked.svg)](http://github.com/badges/stability-badges)
+
+Extend like a boss
+
+xtend is a basic utility library which allows you to extend an object by appending all of the properties from each object in a list. When there are identical properties, the right-most property takes precedence.
+
+## Examples
+
+```js
+var extend = require("xtend")
+
+// extend returns a new object. Does not mutate arguments
+var combination = extend({
+    a: "a",
+    b: "c"
+}, {
+    b: "b"
+})
+// { a: "a", b: "b" }
+```
+
+## Stability status: Locked
+
+## MIT Licensed 
+
+
+  [3]: http://ci.testling.com/Raynos/xtend.png
+  [4]: http://ci.testling.com/Raynos/xtend