Add a Gulp watch task

[thamas]

It should watch changing source files and auto rebuild. It would be nice to have Browsersync added too.

[thamas]

@markconroy's watch setting. Just to have it. :)

gulp.task('watch', 'Watches for your changes and refreshes all the things', function() {
  var config = require('./gulpfile-config.json');
  // Set your localhost address
  browserSync.init({
    proxy: config.browserSync.proxy
  });
  // Watch .scss files
  gulp.watch(['images/sprites/*.png'], ['sprite']);
  gulp.watch(["sass/**/*.scss", "sprites.scss", 'images/**/*'], ['styles:dev']);
  gulp.watch(['css/**/*.css', 'js/**/*.js', 'templates/**/*.html.twig']).on('change', browserSync.reload);
});

[thamas]

Current state

• gulp watch starts BrowserSync and starts to serve the Drupal install (if you configured the local site url)
• gulp watches changes of json, js, twig and css files (in the style guide's source components folder) and
  • runs the build automatically so you don't have to do it manually (but json changes have no effect, you still have to stop and rebuild manually – I do not know the reason yet)
  • reloads the site when css changed (auto reload on other file changes still needs work)