Major system overhaul

[Feliix42]

This absolute unit of a pull request marks a complete visual overhaul of the course management system and also includes numerous bug fixes.

Changelog

• Removed corporate design submodule
• Removed deployment dependencies npm, bower and sassc to provide easier deployment and development (fixes Brainstorming: New Deployment #68)
• Expand news model to include an author name and a publication date for better context
• Altered the contact forms to send all mails fro the course managers internal mail address (fixes Sending mail using own address may not always work #96)
• Added a "contact teacher(s)" form to allow students to get in touch with the teachers of a course easily
• Completely reworked the design of the system based on the Litera Bootstrap theme and thereby fixed Style #24, Permission aware UI #27, Combat Missing Unicode Support On Linux #30, Course Schedule Is Ambiguous #48, White text in Settings #31, Subjects Overview Inconsistent #50, Course administration problems #67 and Links on a public profile are rendered in white (on white background) #71
• Expanded markdown support to news articles and subject info texts
• Squashed all database migrations as they contained cyclic dependencies due to the update to Django 2.2 and previously existing inconsistencies and provided a new working fixture to load in the dev environment
• General cleanup: Removed lots of different modules and functions that were created in the initial development stage but never used

The PR was mainly intended to overhaul the terrible design of the previous beta version. But in the process I found numerous bugs or potential for improvements within the Python code. I tried to remove or rewrite the most unintuitive parts I stumbled upon and tried to clean the project up in general.

Reviews

I know reviewing this absolute piece of work is probably nothing anybody is particularly fond of, so I don't expect any reviews 😄

It's alive!

The contents of this branch are already deployed to https://kurse.ifsr.de.