Adds BW::Location.get_compass & BW::Location.get_compass_once

Returns a hash of a CLHeading object. Example usage:

BW::Location.get_compass do |heading|
  puts heading[:magnetic_heading]
end
Add test to make sure BW::Location.stop stops updating the compass heading.
Typo in get_compass spec.
Changes to readme: add get_compass documentation.
add BW::Deprecated helper so we can deprecate methods
deprecate App.user_cache; fixes #346
BubbleWrap 1.5.0

- Add `BubbleWrap.use_weak_callbacks=(true/false)`, to support `Proc#weak!`
- Add `Camera.popover_from` to show the photo picker on iPad
- Add `Camera.available?`
- Add `UIView#when_screen_edge_panned` gesture shortcut
- Allow #observe to default the first argument to `self` (to observe changes on the same object)
- Fix HTTP connections to run in common run loop modes
- Fix multipart HTTP connections to use `Content-Disposition: attachment`
Merge pull request #348 from markrickert/location-compass

Adds BW::Location.get_compass & BW::Location.get_compass_once
Update readme
Merge branch 'master' of https://github.com/rubymotion/BubbleWrap