update to include header files for googleTagManager, by adding folder to source_files.
pod install started failing with the content of https://dl.google.com/dl/gaformobileapps/GoogleAnalyticsiOS.zip After looking at it, it was because the content was updated to their new 3.0 SDK. I wish they had the version in the URL so we would correctly target each version. For now libGoogleAnalytics.a is not in the zip but the README says we can use libGoogleAnalyticsServices.a which is libGoogleAnalytics.a and the Tag manager lib combined. It's the only option for now.
libGoogleAnalytics_debug.a isn't preserved. Changed the spec to have all .a files included
…e issue #727 for more info.