netdev tests

This application tests the module netdev, it's base module netdev_base in particular. The tests can be automated by running

SENDER=0 make all flash && SENDER=1 make all flash && make test

The values of the network addresses, the channel, and the network ID can be configured by the environment variables

NETDEV_TEST_RECEIVER and NETDEV_TEST_SENDER,
NETDEV_TEST_CHANNEL,
NETDEV_TEST_NID

You can set the role of the application by setting the SENDER variable to either 0 (application is receiver) or any other value (applictation is sender), but keep in mind, that both versions have to be flashed to to seperate devices (identified by RECEIVER_PORT and SENDER_PORT respectively) in order for make test to succeed.