Cleanup linker flags.
Merge pull request #2504 from wordpress-mobile/issue/2503-CleanupLinkerFlags

Cleanup linker flags.
Fixing errors in today widget caused by XCode 6.1
Updating code as per @astralbodies's suggestion
Merge pull request #2513 from wordpress-mobile/issue/fix-today-widget-compile-errors

Fixing errors in today extension caused by XCode 6.1
Merge branch 'develop' into issue/add-lookback-to-project
Added LOOKBACK_ENABLED preprocessor macro.