Unit tests (pull request)

I created a project specifically for unit tests within the Visual Studio solution, which is named PuzzlePathUnitTests. It contains the necessary references needed to use NUnit for unit testing our project, and the nunit.framework.dll is also included within the PuzzlePathUnitTests project folder.

The LauncherTest class contains a few examples of my own unit tests as well. Yes, one test does fail :p I wanted to demonstrate what happens when a test fails.

Make sure you download NUnit itself from here: http://www.nunit.org/index.php?p=download
After you do, compile the unit test project, and open up the resulting PuzzlePathUnitTests.dll within NUnit. Then just hit the "Run" button :p

Also, here's a link to some more documentation: http://www.nunit.org/index.php?p=docHome&r=2.6.2