Added initial support for next TI-sensortag sensors: magnetometer, gyroscope, accelerometer, humidity.

Added response-time for received message. Response-time is needed for integration-time of gyroscope
(unfortunately this a bit unaccurate method). Accurate way should be to get time-stamp from TI-sensortag,
but there is no support from sensortag.

Added setting of the measuring period and notifications (notifications are read during reading any sensor-value,
not event-based yet). Also GATT_ATT-module is updated to support this update.

Added handler (ble_get_string) for getting strings from BLE-device. Added retrieval firmware/software revision in ble_test.c.

Added two more double-parameters in ble_get_float (and corresponding response message-handlers).