Completely remove Pug/Jade in favor of Angular

[tillson]

Currently, the server experiences extra load from being forced to render Pug files.
As it stands, the only data being sent via pug is whether the server is production and if the app is in middle school/upper school mode. These can both be moved into a /api/config GET request or something similar in order to reduce server load.

Additionally, changing from Pug to HTML would decrease the learning curve for contributing to the project.