Ensure all embedded frameworks are signed for Mavericks.

This is just a simple modification to the NSLogger desktop client xcodeproj.  In Mavericks, if any embedded framework is unsigned the app will be labeled 'corrupt' and the user offered a chance to put it into the trash.  In Xcode 5.0.1, if you attempt to code sign an application which has unsigned frameworks, the build step fails.  Since BWToolkitFramework, HockeyApp and HockeyAppSDK's built-in CrashReporter framework are all unsigned, NSLogger fails to build.

This is resolved by adding a new build "run shell" phase, which executes a simple (if somewhat ugly) Python script to walk any embedded frameworks in the built products directory (including frameworks in other frameworks, to catch CrashReporter in HockeyAppSDK), finding those that are unsigned and signing them with the current project build signing identity value.