Initial pass at BW::UIActivityViewController
Patch the Constants class

...so that it doesn't try and bitwise an array of String objects. With passing test.
Update excluded activity types to use better BW::Constants method.
Fix new constants spec.
Merge branch 'refs/heads/master' into uiactivityviewcontroller

* refs/heads/master:
  Do not show warnings about iOS when building for OSX
  Renamed method physical_camera to available in camera_wrapper.
  Added method to check if device has a physical camera.
Merge branch 'refs/heads/master' into uiactivityviewcontroller

* refs/heads/master:
  Update readme
  BubbleWrap 1.5.0
  deprecate App.user_cache; fixes #346
  add BW::Deprecated helper so we can deprecate methods
  Changes to readme: add get_compass documentation.
  Typo in get_compass spec.
  Add test to make sure BW::Location.stop stops updating the compass heading.
  Adds BW::Location.get_compass & BW::Location.get_compass_once
  fix /core and /http to be able to load separately
  1.5.0.rc1
  Add more support for #weak!. Fixes #344
  Remove Motion::Project::Config patch
  Add when_screen_edge_panned for UIScreenEdgePanGestureRecognizer
  Correct bubble-wrap/media dependencies. fixes #339
Allow user to set 'item' or 'items' in the creation of UIActivityViewController
Fix constants test that only works on iOS.
Empty UIActivityViewController specs.
Adds UIActivityController wrapper.
Adds the ability to return an array of constants if the Constant.get doesn't return a number.
Passing test for constants change.
Turns out Apple auto-sets a private transition style that can't be overridden:

17 (which doesn't exist in the UIModalTransitionStyle enum declaration).
Add tests for UIActivityViewController.
Merge branch 'refs/heads/activity-controller' into uiactivityviewcontroller

* refs/heads/activity-controller:
  Add tests for UIActivityViewController.
  Turns out Apple auto-sets a private transition style that can't be overridden:
  Passing test for constants change.
  Adds the ability to return an array of constants if the Constant.get doesn't return a number.
  Adds UIActivityController wrapper.

Conflicts:
	motion/ui/ui_activity_view_controller_wrapper.rb
	motion/util/constants.rb
	spec/motion/util/constants_spec.rb
Removed erroneously committed file.
adds 'BW::NetworkIndicator'
updated README
don't need this block
Update Readme. Add UIActivityViewController documentation.