RxJS Release 2.2.12

This is a minor update from 2.2.12 with the following changes.

ChangeList:

• Fixed TestScheduler.createHotObservable to handle multiple observers Issue #89
• Using MutationObserver or WebKitMutationObserver as a scheduling mechanism Issue #91

The TestScheduler will now use the following logic to determine the fastest immediate scheduling if available:

• MutationObserver or WebKitMutationObserver
• process.nextTick in Node.js
• window.setImmediate
• window.postMessage
• window.MessageChannel
• script.readystatechanged with script injection
• window.setTimeout