Prusa i3 Bowden E3Dv6 Integrated Inductive Sensor Mount

Remix of aaroncm's excellent E3Dv6 mount for Prusa i3.

I've made some changes to make it more to my liking:
* The inductive sensor is integrated in the mount for smaller form factor and higher stability.
* Distances between parts are smaller. This makes the distance between the sensor and the nozzle smaller, and should give you a bigger print surface when using two hot ends.
* More screw holes added for the hot end mount for added stability.

I also removed the sink for the screws attach