Refactored server communication.

Created an interface to handle sending commands.  Refactored as follows:
ICreateController - Implementing classes offer different command
protocols or handling.  Will most likely take an ICreateCommunicator in
the constructor.
ICreateCommunicator - Implementing classes offer different ways to
communicate the commands sent from an ICreateConroller.
Added sign adjustments to comply with Create

The Create needs the sign of distance to match that of velocity and the
sign of an angle to be opposite that of velocity.
Added checking to ensure times are nonnegative.