* Introduce GattServer::initializeGattDatabase(). This populates the GATT
server with added services.
* Add helper funcs: Gap::MSEC_TO_GAP_DURATION_UNITS() to ease setting up of
* Enhance connectionEventCallback() to take in peer addr information.
* Minor cleanup of a few public API classes and removal of unnecessary header-file includes.
* Increase GAP_ADV_PARAMS_INTERVAL_MAX to 0x4000. This addresses mbedmicro/BLE_API/issues/2.
One new API has been added (GattServer::initializeGattDatabase()) and
Gap::ConnectionEventCallback_t has been extended. Applications depending on
these should be updated.