BLE: Add extra logging of pairing process.

The logging now looks like this:
[       24344] ble: connection from B1:94:CF:66:F8:70 opened
[       24757] appDb: store() called, resetting timer
[       25097] ble: Confirm Value: 711617
[       28081] ble: Encrypted handshake successful
[       28083] appDb: store() called, resetting timer
[       28098] appDb: store() called, resetting timer
[       28099] appDb: store() called, resetting timer
[       28101] ble: Secure pairing successful, auth: 0D
[       33101] appDb: STORE_DELAY passed, writing to persistent storage

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>