Add a comment in deb packager explaining the use of fakeroot
Use fakeroot when building RPMs
Raise custom errors when a shell command fails
Remove a TODO comment that is never going to happen
Remove comment about conflation with project and packager

This is no longer true now that a real packaging DSL exists.
Remove unnecessary comment header in software
Default build_retries to 0
Use be(false) instead of be_falsey
Cleanup YARD failures
Use double quotes for DSL files
Update CHANGELOG for 4.0.0 [ci skip]