add docs for helpers
add page for mixins
fixes #16, fixes #17
Merge branch 'origin/master'
several fixes from @tschaub (#16, #17 and some pointed out in comments). Additional cleanup in gruntfile, and rebuild.
Merge branch 'origin/master'

Conflicts:
	src/data/home.yml
	src/templates/pages/docs/Installation.md.hbs
	src/templates/partials/teaser-link.hbs
reapply fixes after merge conflicts