Output the contents of the RPM script, not the path

In the move from FPM to custom packagers, we made an incorrect
assumption that the scripts directive in the RPM spec file contained
the _path_ to the script, not the actual contents. This assumption has
proven to be faulty.

This commit changes the RPM packager and spec to output the contents of
the script file, not the path on disk.
Expose DSL methods in DEB packager for setting various configs
Expose DSL methods in RPM packager for setting various configs
Remove extra comment in PKG packager