Reconnecting Token Generator for Annotation Tool

**Background:** As per Christina's request I'll be turning the Pull Request #2515 into a few smaller PRs. 

**Goal of this PR:** The goal of this PR is to fix two main issues. The first is to use the Firebase Token Generator from the [PyPI version of Firebase](https://pypi.python.org/pypi/firebase-token-generator/1.3.2) and the second is to pass the token as a string rather than create a view (in djangoapp/students) that pops up with the token as a string in the body of the html.

**CMS Updates:** This one still follows the original first push in that Annotator is not yet working in the CMS (this will change in one of the following chunks). In terms of creating a test environment, the Firebase Token Generator uses a different token standard and the current testing backend does not meet those so please email me to ask for a new secret token and url link to the annotation_storage_url. There are no UI changes.

**LMS Updates:** Nothing should change in the UI of the LMS, only the way that the token is handled should change. The secret token and url links have been changed so email me for updates. 

**Testing notes:** Once the proper secret token and URL  are placed you should be able to create annotations in the LMS (*not* the CMS). There is a problem if you get a black bar at the top saying "annotation could not be stored" or if you get a 401 error in the console debugger.