also some quality of life ui improvements

Also removed a bunch of unnecessary code and extracted the test runner into https://gitlab.gwdg.de/grady-corp/grady-test-runner

blub

Also extended existing frontend tests for feedback creation.
In order to fix routing, partially refactored Subscription Vuex module #145

corrected test

Using multiprocessing.Lock to synchronize access to creation of Assignment

fixes #130

Tested with the following piece of code which should hava all edge cases. Works fine :

// should not be commented out
char c = '/*';
String s = "/* some stupid stuff */";

long test(REPLACED k){ /* only this should be commented out */
    if(REPLACED)
        return REPLACED;
    if(REPLACED)
        return REPLACED;
    /* this should be commented out
    if(REPLACED){
        if(REPLACED)
            return REPLACED;
        if(REPLACED)
            return (REPLACED);
    }
   */ this should not
    return 0;
}

fixes #135

Every branch shares the same dev-image and dev-image-base used for caching during the build image step.
On master, only tag commits are built and the image has the tag number

fixes #137

For now, every occurence of "student/s" that is visible to the user has been renamed to "participant". We should however think about how we adress the naming in the future.

fixes #133

At the moment the staging server is kinda broken and the functional tests already ensure that the app is not completely broken