Add page count and links to bottom of board view

Current page shows up on the bottom of every board with next/prev links
where applicable.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

board/static/board/style.css

@@ -19,6 +19,13 @@ hr {
     font-size: small;
 }
 
+/* Pagination */
+.pagination {
+    margin: auto;
+    width: 50%;
+    text-align: center;
+}
+
 /* Posts */
 /*.post_body { }*/
 .post_image_info {