Now condtions are anded together and can also be removed

Just a tiny little utility

Accounting more special cases. Also added tests where appropriate

Since SLF4J is loaded out of necessity in the test run time we cannot test the case of it not being loaded.

First time we're testing if we can use external libraries as is

 by requiring to pass the class instance of that along. Additionally we perform checks if the new instance is of the correct type.

Also prevent the ClassLoader from loading itself ever!

The classes are now called ...Bootstrapper
Also restructured some of the code to be closer to what we would expect to have in a real environment

That is needed because else the ClassLoader wouldn't be easily accessible

There's a lot more that needs to be tested!

Also moved some files around

Also added a few utility constructors

+ Better documentation
- Removed some unused `@SuppressFBWarnings` annotations

First refactoring of the DependencyDownloader class

Now onto generalizing and adjusting

[ci skip]