Require a changed firmware password before upload. (#576)
Require a changed firmware password before upload. (#576)

Require that the user changes the default HTTP password before we allow
OTA firmware upload.
- Remove 'FIRMWARE_OTA_PASSWORD_ENABLE'. It's now always on.
- Rework user settings so it's more obvious where and what they can change.
- Add option to ignore 'UNKNOWN' IR messages that are received via IR.
- Warn the user if they have enabled OTA updates, but not changed the password.
- Other minor cleanups.
- Fix issue with DEBUG. i.e. incorrectly used `#ifdef` instead of `#if`

Tested: FIRMWARE_OTA, REPORT_UNKNOWNS, & changed/unchanged default password
        on a D1 Mini, and a Nodemcu device.

Ref: #574 #575
markszabo/IRremoteESP8266,markszabo/IRremoteESP8266,markszabo/IRremoteESP8266,markszabo/IRremoteESP8266