Update readme

Add downloading of corresponding DeviceFamilyPack in bootstrap script

🚚 change GitHub organization to NordicPlayground

Merge header file changes

* 'master' of https://github.com/NordicSemiconductor/pc-ble-driver: (52 commits)
  Re-add sdk folder to ignore file
  Remove commented out lines
  Add missing handling of keyset
  Updated fix, build test is required
  Fixed building issue on Linux
  Simplify baud rate logic by specifying init values
  Fixed whitespacing issue in the code copied from sdk
  Fixed merge conflict in app_ble_gap_sec_keys.cpp in v5
  Fixed merge conflict in ble_gap_evt_app.c in v5
  Fixed merge conflict in app_ble_gap_sec_keys.h in v5
  Fixed merge conflict in ble_gap_impl.cpp
  Update connectivity hex files
  Update connectivity hex files
  Add optional command line argument for specifying baud rate
  Reduce max packet size
  Re-add changes that were mistakenly removed
  Add script for donwloading sdk
  Bump version number in connectivity patch files
  Add updated v2 connectivity hex files
  Remove references to v3
  ...

Feature/s132v5

Using implementation from SDK unchanged instead