Add minification of resources to workflow

[joseluis]

CSS

• Benchmarks of css minification engines & repo
• gulp more-css
• gulp uncss

SVG

• svgo | github

HTML

• htmlclean | github (simple)
• >html-minifier | github
• html compressor (repo)
• minimize (repo) (imperfect)

CONCATENATION

• concat | github

MISC.

Find more packages in nipster & more