Extruder Calibration Tool V2

This is the next iteration in the design of an [extruder calibration tool](http://www.thingiverse.com/thing:109601) I use to help with the calibration of the extruder on the Felix Printer. I was frustrated with inaccuracy of marking filament and trying to measure with my callipers.

##Updated in this Version:
- Fixed, the Top piece was not sitting flush with the Z axis in the original STL file, as a result unnecessary support would be printed under it.
- Fixed, 1.75mm fiiment now presses s