Clean lecture test
Switch to non deprecated methods
Add support for LectureGroupTaskSheet API

Also simplify the database behind them and resolve the n:m connection to a
simplier one for easier use.

Also implement the new ConnectionEntity API and removes the old
ConnectWithEntity API. See library commit
47828135ddb29bec7ad00cec93e6c2f9b691d3d0 for more information about it.

Use JUnit SuitCase testing instead of single tests to solve the problem
with Unit testing of each part(lecture and task part) and the Unit testing
of the relation between them (taskSheet and lectureGroupTaskSheet). Sweet
thing, the run time of the tests is reduced using one http server for all
tests instead starting and stopping one for every test and also whipe
database at the start of all tests instead of whiping the database at
every test.