drivers/srf02: adapted ultrasonic ranger driver to general i2c interface

This PR is based on  #1859. It changes the i2c commands in the sensor-driver to the general interface definition. It also adds a small test.
I'd prefer something like
```c
while (1) {
    val = srf02_read(srf_device);
    printf("Distance Reading: %i cm/inch\n", val);
}
```