Add unit tests to the solution

[Craig Phillips]

Add unit tests to the solution to exercise all of the functionality of the stampver program, performing the necessary refactoring that's required to support this. (i.e. The main functionality of the Stampver program is currently contained within the console application's Main() entry point method and is currently dependent upon calls to various System.IO classes and methods.

[Craig Phillips]

Resolves #4 - Added the final set of unit tests for the dryrun parameter.

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