Patient zipper decomplexify

Broke up the methods in `Cypress::PatientZipper` to be less complex. 

I didn't focus on making the class more OO, because each method is really only used in one place, and takes different arguments. 

Also made some grammatical corrections, and removed an unused constant.

Pushed down the `max_violations` to 5 (the 3 in this PR, and one from Andy), and the code coverage up to 77.78%.