Facebook iOS SDK 3.11

Summary:
     see https://developers.facebook.com/ios/change-log-3.x/

Upgrading:
     https://developers.facebook.com/docs/ios/upgrading/

Reviewed By: jacl

Test Plan: Release Testing.
Merge branch 'master' of https://github.com/facebook/facebook-ios-sdk
Finish integration/upgrade to 3.11.0