Major release

This release introduces a list of breaking changes. Anyway common use cases shouldn't be affected.

Breaking Changes

Updated to Gulp4 (#18)
dev task removed. Just run gulp
Internal tasks clean:tmp, bump:type are no more available as public tasks
remote task now executes a deploy of the contents in public folder based on the global or host's specific deployStrategy property. Replaces ftp and rsync tasks.
modernizr:html5shiv task removed
Nunjuck views now default to .njk extension. For compatibility, HTML files will be rendered as well, though.
viewmatch property in build/gulp-config/properties.js has been replaced by viewsExt: [...].
Dropped support for IE9 (#17)
audio and video folders are now stored under a common application/assets/media folder. Added a media path key in build/gulp-config/paths.js
Using browserslist keyword in package.json for autoprefixer and Babel presets. See README.md for supported browsers
Updated default sans-serif font families (#16)
New build/gulp-tasks/lib/renderers structure. Early support for multiple and external view renderers