* Remove Guava dependency from WebGoat
* Add Checkstyle to the project with very basic standards so we have a
style across lessons. It does not interfere with basic Intellij formatting
- Now using Spring Boot for classloading, this way local development does not need to restart the complete server
- Fixed all kinds of dependencies on the names of the lessons necessary to keep in mind during the creation of a lesson.
- Simplied loading of resources, by adding resource mappings in MvcConfig.
- Refactored plugin loading, now only one class is left for loading the lessons.
Squashing and merging ...
* Each assigment should have the options to have its own set of hints #278
* Updating lessons due to changes from #278
* Enable i18n client side #312
* IDOR move hints to assignment and enable i18n #312
do not need to support anymore in 8.0:
- Introduced DI thoughout the code base
- Removed most superclasses of a lesson
- Hammerhead is now simplified to only one line of code
- Cleaned up WebSession
- Removed code which dealt with user roles, lesson fetching, username etc
- LessonTracker improvements
- Removed almost all code from the Screen class
- Removed ECS from the container project
- Removed adminstration pages, contained a lot of ECS codes which is much
simpler to just rewrite when necessary
