Add picture-nail mounting holes to printed PCB base

[connornishijima]

• On the printed base, under the Sweet Spot LEDs, should be an integrated wall hanging solution to compliment the use of Headless Mode, defined in Issue #2.
• This position allows the power and LED wires to exit via the bottom of the mounted unit.
• The design should be a toothed mount, similar to a picture frame, 1" wide, and have and integrated backing wall to prevent the hanging nails from reaching the PCB.
• The toothed design allows users to balance the unit properly even with only one mounting nail.