refactor the methods to create the embedded mongo instance into extra class
refactor tests dealing with the url collection in its own test class
remove unused urlinfo
refactor UrlDB to UrlsCollection
change varnames in TestUrlCollectionInteraction
add notes with multiple todos
add failing test when trying to add multiple urls
improve, but not pass, test by using a method with after annotation to clear the collection after the test
pass test, dealt wrong with the cursor
add some todo notes concerning the usage of spark