support packaging of applications

[majewsky]

• allow to mark files/dirs/symlinks as "not configuration" (so that they are just overwritten on upgrade instead of being treated by the config file update logic of the package manager) using a new attribute like role = "static" (where the default is role = "config")
• allow to set a package-wide default for that role attribute (again, default is config)
• allow to import a directory including subdirectories from the filesystem (similar to how contentFrom imports a file from the filesystem)