Improve footer

- Moved container class into footer.
- Added py-3 for footer padding. Not sure if I prefer this to using the stylesheet.
- Replaced hr with border-top.

src/components/footer.svelte

@@ -1,6 +1,3 @@
-<footer>
-    <div class="container">
-        <hr>
-        <p>&copy; Quartznet 2020 | <a href="./policy">Policy</a></p>
-    </div>
+<footer class="container py-3">
+    <p>&copy; Quartznet 2020 | <a href="./policy">Policy</a></p>
 </footer>