Add sensor HAL test program

Add sensor HAL test program

This patch adds a HAL test program that can be used to test the sensor
HAL in a console Android environment (e.g. not framework
required). This is useful for faster development for sensor drivers
and HAL features as well as for faster enabling on new platforms.

The test program takes the following commands: start HAL, stop HAL,
list sensors, activate and deactivate sensors, and set delay.

The start command will fork, load the HAL shared object, initialize it
and keep it running in the background. One thread will be used for
polling sensor data and one for accepting commands from the
client. UNIX sockets are used for communication between the client and
server.

Change-Id: I837e1dd9cb48657d4a8fe52f67c751e619b5c244
Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>