Refactoring exercise 2

[lucasverleyen]

The example solution sent by email (which can be found in the zip file on the shared drive) is not fully correct. The constant heating input in section 4 of exercise 2 is lacking. However, when we have merged the latest IBPSA library into IDEAS, we can rely on the SimpleHouse model from IBPSA and modify our crash course assignment accordingly. Subsequently, we don't have to send a zip file with the solutions and we can refer to the examples and tutorials in the IDEAS library. This issue is to update the crash course exercise 2 according to the SimpleHouse tutorial in IBPSA.