+ a little bit of props refactor

Fixed the bug when the admin browses the solutions and the student uploads a solution during this, the admin did not see the new solution. Now works correctly.

You can now create new tasks and upload a solution (or more) for them.

Listing the tasks based by its properties and states, also counting with empty lists.

Footer should be always fixed to the bottom, though you may need to use margins at the bottom element.