removed nameless constants, added clear key state
- also fixed some lexical errors discovered during visual code review
* Calc.csproj: added presenter interface

* MockCalculator.cs: added a mock calculator for quick manual sanity
  check

* App.cs: modified construct the calculator presenter

* Keypad.cs: modified keypad to encorporate the calculator presenter

* ICalculator.cs: this is the calculator presenter interface
* Calc.sln: added number entry mediator

* TraditionalCalculator.cs: traditional calculator 

* SkunkTest.csproj: basic sanity test harness

* TestNumericEntryMediator.cs: test cases for numeric entry mediator

* packages.config: 

* App.cs: changed to use TraditionalCalculator as presenter


* Calc.csproj: m

* Keypad.cs:
* ICalculator.cs: moved to Presenter

* MockCalculator.cs: moved to presenter

* ICalculator.cs:
* MockCalculator.cs: moved

* NumericEntryMediator.cs: created mediator to handle numeric input