Summary:
Changelog: [Internal] changing the extention from AppDelegate.m to AppDelegate.mm in the app template to support the new architecture.
Most changes were generated when opening the xcworkspace.
Reviewed By: cortinico
Differential Revision: D33051442
fbshipit-source-id: f472a9df26db11a02fc9f7d0544f0207e7c3e7ca