added simulation controller to documentation
added Use Case Diagram
I added an "if (scenarios.isEmpty())" section into the constructor of SimulationController. I left it in comments under the original code, because it won't work until Shaunt's method is in the code. He said before that he's thinking the "addRandomScenario()" method will be in SimulationController. If it is not, we'll have to add in an instance of whatever class the method can be found in.

This code is currently written with some assumptions about Shaunt's method.
added a simple, temporary random scenario button
Merge pull request #4 from jkuk/master

added random scenario button for shaunt
Merge pull request #3 from RichardHayesMassbay/master

Added code to SimulationController constructor
Merge remote-tracking branch 'upstream/master'