build-a-not-nand-gate: Fixes after presentation

- Set all resistors to 5-band 1%, so the bands in the breadboard diagrams
  match the kits.

- Move the addition of the input LED of the NOT gate from step 1 to step
  2, so people aren't tempted to wire the LED directly to ground without
  a current-limiting resistor.

- Remove blue air-wire from one of the intermediate NAND gate Fritzing
  files.

- Add color to the gate truth tables.