OpenScad model of servo 9g

In order to estimate the position of a servo in a 3D printed component designed in OpenSCAD, a model of a servo is extremely helpful.

Here I have remixed the model from RafaelEstevam (http://www.thingiverse.com/thing:1621168) by setting the origin of the axis of coordinates in the shaft of the servo motor. This improvement facilitates the use of the servo model as a module that can be translated by defining the x, y and z components in the function servo9g(x,y,z);