Added new test; little bit of refactoring.

Changed the word "sigma" to "variance" to better indicate the reasoning.
Added in a new test ("ratio test"), including helper function in there.
Added a function variable in main to cleanly switch from one test to another.
Added an if conditional on the fourth test to make sure it's not the "ratio test" which runs too slowly.
Removed print statement in createConnectionMatrix.
Hey Ben, that is a pretty big issue in the code, then! The Gaussian assumes that what you're passing in is the covariance matrix (i.e. variance)! Which means when you had been giving me [[0,15], [15,0]], that was being interpreted as [[0, ~3.87], [~3.87, 0]]. I changed the variable from sigma to variance specifically to reflect the fact that the parameter/ variable being used was the  square of the standard deviation! If you want the SD to be 15, then we'll have to square the parameter passed in before using it in the Gaussian! Which should it be?