This resolves some warnings from phpunit about the getMock versus createMock (the suggested way).
I'm assuming that this will be a 2.0.0 tagged bump due to BC breakage.
I'm assuming that setting the minimum to PHP 5.6 is perfectly acceptable because even phpunit complains about 5.5. Furthermore, major distributions of linux are now including php 7 at this juncture and providing legacy support for security-only versions of PHP is sub-optimal from a forward-looking perspective.
Resolves #90 and #103