Sense Hat: LSM9DS1 sensor driver

[leinardi]

Hi, I know that currently you are not accepting external contributions for new drivers but, in case you will open contribution again, I would like to make a PR for the LSM9DS1, the 3D accelerometer, 3D gyroscope, 3D magnetometer and temperature sensor used also in the Sense Hat.

Meanwhile I published the driver on JCenter, more info here: https://github.com/leinardi/androidthings-drivers/tree/master/driver-lsm9ds1

[proppy]

Related #24