Examples: Fix Knock.
Examples: Fix Knock.

Configure sensor pin for analog input.  Genericize with BOARD_LED_PIN.
Fix whitespace.  Use toggleLED() instead of keeping track of the LED
state by hand.  Fix the comment about why we delay.  Fix whitespace.

leaflabs/maple-ide,leaflabs/maple-ide,leaflabs/maple-ide,leaflabs/maple-ide,leaflabs/maple-ide