correct from feedback (+1 squashed commits)

Squashed commits:

[6e4fff9] Bug fix, plus corrected tests (+1 squashed commits)

Squashed commits:

[552f53e] Create failing test to highlight problem creating UNC paths.  Create two other tests for other UNC related commands that should throw an exception.
Merge branch 'CreateDirectory_WorksWithUNC' of https://github.com/vtjdailey/System.IO.Abstractions into CreateDirectory_WorksWithUNC