Fix/attrs

_based on changelog (see #41) treeline_

All lines in %files block will be generated based on processFiles() function
 using grunt.template.process().

 Side-Effects: Shaves off LOC significantly and makes control-flow
 significantly more concise/readable.

 Also removes reliance on calling chown/chgrp in %post-block.
 Which normally triggers rpmlint's `dangerous-command-in-%post`