Added test cases to branch for increasing coverage

[samprity]

Hello,

We are engineering students in Canada. As a part of our course assignment on "software testing", we chose your project. Course is about writing the test cases. We wrote 16 test cases to increase the coverage for your code. Earlier the test coverage was 79% and after adding the test cases, it increased to 80.1%. We added the test cases for following classes:-

1. StateMachineManagement.java (51% coverage)
2. ManagementService.java (77.9% coverage)
3. Pair.java(70.3% coverage)

It will be very helpful if you can accept our test pull request, so that we can get the grades for the assignment.

Thanks
Samprity