Update SimulationController.java

Cleaned and optimized addRandomizedScenario() method 
Removed readCore() method (moved to addRandomizedScenario())
Merge pull request #17 from elimin8er54/patch-3

Update SimulationController.java
Ketty's changes: Fixed user log in issues, updated Student Manager
Merge pull request #18 from sadasilva/master

Changes made
Merge pull request #19 from jkuk/master

Ketty's changes
More changes: make windows not sit on top of everything, wording and typos, when time is up save all changes and exit to scenario panel.