The coap communication is achieved by attaching a key as data to each event callback. In
the callback, the key press is assmebled into a CoAP package that is
sent to a currently hard coded address of the CoAP server listening on
port 5843.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@huawei.com>
Signed-off-by: Luca Seritan <luca.seritan@huawei.com>

Use Apache-2.0 for compatiblity with other zephyr sources.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>