PUBLISHED_FROM=2babde0d0c6add14aa500f4bf1c833715d979c6c

And also fix `flash` target for nrf51

PUBLISHED_FROM=decc6242380eb7070bfbcb26c57780e756588cc3

This reverts commit 1a17e17c462bdd4e1d26d8742f8b7087273e04c2.

PUBLISHED_FROM=80028de308c9a021955d1425d2bfee8feb85f193

PUBLISHED_FROM=ea64670e42ae58bbe26abee5d928f2afcd83bd46

And pre-create directories for SDK for both nRF51 and nRF52.

PUBLISHED_FROM=00caf156f48da92804c6af8efe323535fbc5497d

Now all warnings are disabled on SDK files, and enabled on our
application's files.

Fixed a couple of things in nRF52 which were unnoticed because all
warnings were disabled there from the beginning.

PUBLISHED_FROM=a33ab22d0ce85efea364b80478986b88f4b0a3a2

Now it works in hardware.

PUBLISHED_FROM=f223bde2d2bebe97513ce073eb887552bc3d93af

Keil actually saves project on disk only when the project is closed,
that's why these changes were missing before

PUBLISHED_FROM=d8ebdaa009ff5676bf6c16aaa2fe8356b03d3b8b

PUBLISHED_FROM=7b02f8e7bb85ce1b45f872610645e619de5e313a

PUBLISHED_FROM=b860ada45e76b0e04d214fedb04f5a7dd9c7d8f0

By making dir hierarchy replicate that of examples provided with the nRF
IoT SDK.

Also, example for Keil uVision IDE is added.

PUBLISHED_FROM=1a3d9a54d15eb1acfb1b5d162138576a387ed21c

PUBLISHED_FROM=d9d979057d5269ac32d16545dd2489485bda642a