Secure proximity profile example using LLS and LEDs

- Establish an unauthenticated, encrypted link with bonding with an LLS
client (iPhone/Android/CySmart tools)

- Trigger Blue LED alerts on 042-BLE kit when the RSSI is below a
particular threshold if the Alert Level characteristics is configured to
do so by the LLS Client.

- Advertises for the first 15 seconds to connect with any Central device
(this can be done also by detecting a key press event for example)

- Switches over to advertise/connect with devices on the whitelist
(previously paired/bonded devices) for the next 15 seconds

See project schematic page for more description and testing details