Add blogcard shortcode for embedding Hatenablog cards

Author: shunk031

layouts/shortcodes/blogcard.html

@@ -0,0 +1,5 @@
+<div class="blogcard">
+    <iframe class="hatenablogcard" style="width:100%;height:155px;max-width:500px;"
+        src="https://hatenablog-parts.com/embed?url={{ .Get " url" }}" width="300" height="150" frameborder="0"
+        scrolling="no"></iframe>
+</div>