renamed common.py to driver_base.py and updated sprinter_reprap/__init__.py to point to it
added classes to describe the paramaters of different types of printers.  A driver should report one of these.
offloaded functions for processing gcode responses to their own file for code reuse.
offloaded functions for processing gcode responses to their own file for code reuse.
offloaded functions for processing gcode responses to their own file for code reuse.
Issue #29 implemented some classes which drivers can report their capabilities with.  Sprinter driver now uses these to report its hardware configuration.