robot_spec #orient tests that when a robot is given a valid direction, it sets the robot's orientation.
#orient tests that if an invalid direction is given, an ArgumentError is raised
Robot#turn_right

Given an orientation, this method instructs the robot to turn right.
implement Robot#turn_right
implement robot's gps system
include gps.rb in spec_helper
robot_spec Robot#turn_left

Given a robot's orientation, instructs the robot to turn left.
implement Robot#turn_left
robot_spec Robot#at

Set's the robot in an x,y coordinate position in the grid.