Move test convenience function
Provide coverage for _process_when_build_dependency
Refactor the package loading and postprocessing
Allow globs in "files:" entry of build stages

The globs are matched relative to the package directory. The auxiliary
PackageYAML class is used to remember the package directory, if any.
Better error logging when loading packages
Move MockProfile attributes to instance
Fix typo
Merge pull request #257 from vbraun/files_glob

Files globs