frank-update should delete frankified build or indicate that you should perform a clean

[rhgills]

After running frank update to update one or more libraries included with Frank, the frankified_build directory should be deleted with the users permission, or the user warned of the following.

If the user typically runs frank build --no-clean, any changes to the Frank static libraries will not be included in the frankified app until such time as a rebuild of the app is necessary or the frankified_build directory is manually deleted.