Re-organise project and use load-grunt-configs
Fix scsslint issue.

At this point, the contents of the scss directory are somewhat redundant, but may be added to later on.
Move grunt task configurations
Add explicit HTML5 feature support
Change textdomain
Add .csscomb.json config
Move custom tasks to new files
Add grunt-newer and develop branch of grunt-wp-i18n
Tidy up Gruntfile.js