RunInfo is a central object that controls the run of the performance
test. It is not intended to be inherited nor extended. It is just a central piece that
tells us when the test started, for how long it runs, when it should finish and how many
iteration have already passed since the test start.
RunInfo typically originates in the scenario definition. The scenario
can specify the length of the performance test in either a time unit (milliseconds) or
number of iterations (how many messages should be sent).
RunInfo is passed to many other objects in PerfCake but it is not
supposed to be modified. It is a good practice to use it just for obtaining information
about the running test by using its getters.