Add build using polymer-build (#344)

* Add build using polymer-build

* Use bundle strategies to tweak stripExcludes

* Only vulcanize hass.io panel

* Rename hassio panel generate script

* Remove hydrolysis

* Get it all somewhat working

* Fixes

* Allow ES2015 + fix minify JS

* Clarify we need to fix service worker minify

* Move service worker template out of tasks folder

* Fix broken CSS

* Wrap it up

* Fix maps

gulp/tasks/default.js

@@ -0,0 +1,9 @@
+import gulp from 'gulp';
+import runSequence from 'run-sequence';
+
+gulp.task('default', () => {
+  return runSequence.use(gulp)(
+    'clean',
+    'build',
+  );
+});