added OpenBeacon firmware for Physical Web support

Similar to the other examples in the physical-web firmware directory that file expects to be compiled in an development environment. In this case it is maintained as part of the OpenBeacon project (generic library for BLE and proximity communication on top of the nRF51822 chip).

See Makefile at:
https://github.com/meriac/openbeacon-ng/tree/master/firmware/nRF51/tag-physical-web