lm8uu's mounted to y-carriage, zip tie holes along z bottom, removed motor mounts

Latest revision obsoletes three LM8UU plastic parts on the underside of
the y-carriage and has them directly mounted to the y-carriage with zip
ties. Four holes added to the bottom of the frame for holding wires in
place with zip ties. Removed Printrboard mount holes. Removed motor
mounts.
initial commit