Merge pull request #106 from fillito/pull_requests/weak_instead_unsafeunretained

Use weak instead of unsafe_unretained if the deployment target is set to 5.0 or above.
Update to the latest CocoaPods and update some pods.
Prefer defined constant over raw value
Merge pull request #105 from fillito/pull_requests/arc_ios6

ARC iOS 6 compatibility: display_release/retain is not needed on iOS6 and will cause a build failure if the deployment target is set to 6.0 or greater.
Update Gemfile and Ruby version, trying to get Travis working
Re-added ios-sim-test, link libPods to the unit tests target.
Always clean when testing.
Until I can get unit tests running on Travis, just build for now
Added build status image
It helps if you use the correct URL.
check isConnected before sending Event
Merge branch 'pull_requests/ptpusherconnection_contract' of https://github.com/fillito/libPusher
Merge branch 'master' of https://github.com/lukeredpath/libPusher