Update configuration comments in nrsysmond.cfg
Add labels option to nrsysmond.cfg
Only deploy config comments of configuration options actually used

This helps dealing with a bug in nrsysmond when using too long config files
Remove spaces between square brackets
Remove redundant brackets
Use || instead of or
Add trailing comma
Use %w() in metadata.rb
Use File.exist?
Fix case indention
Use single quotes when no interpolation is needed
Remove extra blank lines
Use do/end instead of {} for multi-line block
Remove redundant return
Add rubocop configuration
Bump version to 0.5.3, update CHANGELOG