nRF52 example project

This is a Mongoose "Hello, world" that can be compiled under nRF IoT SDK.

To make it work, you should download nRF5 IoT SDK and unpack it in the current directory as nrf5_iot_sdk.

The project structure replicates that of the examples provided with the SDK: Keil uVision project is located at boards/pca10040/arm5_no_packs; ARM-GCC Makefile is located in boards/pca10040/armgcc.