Add trailing slash to certain (directory) links

Google Search indexing apparently complains when you don't have a
trailing slash for directory-style links. For example:
`/blog/categories`
redirecting to
`/blog/categories/`
is not kosher. Looking at curl indicates that there is a proper 301
redirection.

_layouts/post.html

@@ -18,7 +18,7 @@ <h2>{{ page.title }}</h2>
   <div>
     <p>
       <b>Posted:</b> {{ page.date | date: "%B %e, %Y" }} in
-      <a href="/blog/categories/{{ page.category }}">{{ page.category }}</a>. {%
+      <a href="/blog/categories/{{ page.category }}/">{{ page.category }}</a>. {%
       if page.last_modified_at %}
       <i
         ><b>Last Updated:</b> {{ page.last_modified_at | date: "%B %e, %Y" }}</i
@@ -40,7 +40,7 @@ <h2>{{ page.title }}</h2>
   <div id="tags">
     <b>Tags: </b>
     {% for tag in page.tags %}
-    <a href="/blog/tags/{{ tag }}" class="taglink">{{ tag }}</a>
+    <a href="/blog/tags/{{ tag }}/" class="taglink">{{ tag }}</a>
     {% endfor %}
   </div>
   {% endif %}

blog/categories/index.html

@@ -23,7 +23,7 @@ <h2>Post by Category:</h2>
   {% assign sortedcats = categories | split:' ' | sort %}
 
 {% for category in sortedcats %}
-  <h3 id="{{ category }}"><a href="{{page.dir}}{{ category }}">{{ category }}</a></h3>
+  <h3 id="{{ category }}"><a href="{{page.dir}}{{ category }}/">{{ category }}</a></h3>
   <ul>
   {% for post in site.categories[category] %}
     <li><a href="{{ post.url }}">{{ post.title }}</a></li>

blog/index.md

@@ -29,7 +29,7 @@ redirect_from: /blog.html
     </h3>
     <p>
       <b>Posted:</b> {{ post.date | date: "%B %e, %Y" }} in
-      <a href="/blog/categories/{{ post.category }}">{{ post.category }}</a>. {%
+      <a href="/blog/categories/{{ post.category }}/">{{ post.category }}</a>. {%
       if post.last_modified_at %}
       <i
         ><b>Last Updated:</b> {{ post.last_modified_at | date: "%B %e, %Y" }}</i

blog/tags/index.html

@@ -23,7 +23,7 @@ <h2>Post by Tag:</h2>
   {% assign sortedtags = tags | split:' ' | sort %}
 
 {% for tag in sortedtags %}
-  <h3 id="{{ tag }}"><a href="{{page.dir}}{{ tag }}">{{ tag }}</a></h3>
+  <h3 id="{{ tag }}"><a href="{{page.dir}}{{ tag }}/">{{ tag }}</a></h3>
   <ul>
   {% for post in site.tags[tag] %}
     <li><a href="{{ post.url }}">{{ post.title }}</a></li>