Led Ring for Prusa i3 Hephestos - improvements

Work in progress improvements to "Led Ring for Prusa i3 Hephestos by LinusHack", added: led contact track and cable exit.

UPDATE: v3 is functional and working, see pictures.

Electronics: 5 Hi-Bright LED in parallel, 2V, 20mA (circa 500 Ohm resistor for 12V source)

v3: added cover
v2: corrected some misplacements and "pugs" (3d printing bugs)