Update karma_calculator_spec file

My story: https://www.pivotaltracker.com/story/show/82978024
I wrote an it block to make every statement executed al least once. Thus increase coverage of the test. Only the changes to karma_calculator_spec relates to the chores. Other changes I made is my setup attempts and coverage testing on my machines.
Have you considered using `context` with these blocks? See http://betterspecs.org/#contexts. The way I see it, the setup code right now is adding considerable noise to the expectation (8 lines of setup vs 1 line of expectation).

A side note: don’t feel you have to be constrained to follow the style the current test uses, in fact, if you feel you could make them better, you are more than welcome to do so. This is a refactoring exercise so improving existing code is within the scope of the story.