am 1970cb3a: Add a sample showing the use of the step sensors (STEP_DETECTOR and STEP_COUNTER) and sensor event batching.

* commit '1970cb3a4d24874e57e133f0adbfa83e4603e9f7':
  Add a sample showing the use of the step sensors (STEP_DETECTOR and STEP_COUNTER) and sensor event batching.