Build: update build.sh to generate Acknowledgements

- Discarded plans for in app Acknowledgements for now.
  ran into multiple issue around UI at this time. For
  one info button overlay on map view is not very
  responsive to touches.

- Added credits.py 3rd-party script

- Acknowledgements.plist generated for Settings.bundle
  and can be seen by going to settings->iGCS in iOS.

- Excluded HockeySDK from Acknowledgements.plist since
  it won't ship to app store.