Improve build times

* Fix bulma/buefy being imported many (many !!!) times

* Remove javascript-time-ago because date-fns pretty much does the same
thing

* Make sure languages are loaded asynchronously

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

js/src/views/Posts/Post.vue

@@ -129,8 +129,6 @@ export default class Post extends Vue {
 }
 </script>
 <style lang="scss" scoped>
-@import "../../variables.scss";
-
 article {
   section.heading-section {
     text-align: center;