* Controller.cs: Implement a controller to execute commands

* PlayVideoCommand.cs:
* PlayMusicCommand.cs:
* PlayPowerpointCommand.cs: Update to the new interface and Add in a
  basic set of commands to recognize

* ICommand.cs: Add in a List<String> of Commands that should be
  checked
* PlayMusicCommand.cs: Simplify and improve the PlayMusisCommand
  class 

* PlayPowerpointCommand.cs: Simplify and improve the
  PlayPowerPointCommand allowing a random powerpoint to be played from
  the My Documents folder or a path specified at instantiation

* PlayVideoCommand.cs: Simplify and Improve PlayVideoCommand

* ICommand.cs: Slim down the interface and remove the unnecessary
  string parameter

* Controller.cs: Add ability to go with a default set of commands or
  add your own set of command classes at instantiation, also refactor
  the execution to use new ICommand interface
* FileCommand.cs: Refactor common file operations out into an
  abstract class

* Controller.cs: ensure that the command is lowercase when checking
  for occurance

* ICommand.cs: loosen the Interface a bit

* Krystal.Core.csproj: add FileCommand

* PlayMusicCommand.cs: Refactor PlayMusicCommand to use FileCommand

* PlayPowerpointCommand.cs: Refactor PlayPowerpointCommand to use
  FileCommand base class

* PlayVideoCommand.cs: refactor PlayVideoCommand to use FileCommand
  Base Class
Refactor to use Krystal.Core
Refactor Namespace to Krystal.Voice