Moved check logic to new method to be able to write more thorough unit tests

Many of the checks introduced in the VIP parameters check could not be exercised since the only checks in place so far were for the first parameter of a single parameter function. By moving the checking logic to a separate method that received the file path, file contents and list of checks as arguments, more thorough unit tests can be written.
Augmented and updated test suite for VIPParametersCheck class

Added multiple tests to exercise all of the checking capabilities of VIPParametersCheck class.

Renamed one test to have clearer name.