Moved VacuousModel code into InitialiseComponentTest as it is the only
place where it is to be used
Testing for ABCMethodTest
Added test to ABCMethod to test when None is returned in the option,
refactored common code
First draft of tests for IterateComponent
Refactored common code in IterateComponentTest
Removed Before annotation from ABCMethodTest
Merge branch 'develop' of https://github.com/tearne/Sampler.git into develop