Added StepperMotor Module

__Added a module to simulate a Stepper Motor. Uses PyQt4 for GUI.__

This essentially uses `setPixmap` to update a label in a pyqt window with the image of gear and shaft ( The F.V of a StepperMotor ) rotated by an angle which corresponds to the position of the stepper motor. The position is either updated by calling any of the methods `rotate()`, `move_to()` and `move_by()` or by altering the states of the connectors set to it ( which are stored in the `leads` list ) and calling `trigger()` which checks for the change and corresponds it with the `SEQ` ( a list of valid sequence ) and updates the `angle`.

The added stepper motor is Bipolar and Dual mode ( Full Step mode and Half Step mode ).