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.
I actually think this is an important test.  One hidden unit is enough, but making sure the algorithm can completely fill the connectivity matrix is a good one.  I would keep this.