Update templates & fix carousel bugs

Templates now have date of 2019 BBC Young Reporter day on them;
Carousel bug whereby if a dot was clicked & then the used scrolled away, 
the dot would turn black;
Dots now appear in the correct position on all screen sizes (they were 
too low on mobile).

_posts/_template/2019-03-06-image-article-name.md

@@ -0,0 +1,10 @@
+---
+title: Title
+date: 2019-03-06 7:01
+authors: Name
+image-caption: A caption for the cover image
+layout: image-article
+categories: articles
+---
+
+Content