Smartrap Mini - Improvements in the X and Y axis

Based on the Smartrap Mini from [Smartfriendz](http://www.thingiverse.com/smartfriendz) project.
http://www.thingiverse.com/thing:177256.

The project intends to introduce a number of improvements to the movement of the X and Y axes to make it smoother and more precise. These improvements do not require modifications to the original design of the pieces of the printer, as it is only necessary to make specific holes to accommodate the screws that hold the bearings acting as tensors. The whole