igcs 114 attribution file view

- Discarded plans for in app Acknowledgements for now.
  Ran into multiple issues around UI. For one info button
  overlay on map view is not very responsive to touches and
  I was probably going to have to put the text in a webview.

- Added credits.py 3rd-party script

- Acknowledgements.plist generated for Settings.bundle
  and can be seen by going to settings->iGCS in iOS as
  is current app marketing version and build.

- Excluded HockeySDK from Acknowledgements.plist since
  it won't ship to app store.
@andymoe, left-over cruft.