resolves #8 add RSS feed template

feed.xml

@@ -0,0 +1,38 @@
+---
+layout: null
+---
+
+<?xml version="1.0" encoding="UTF-8"?>
+<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">
+  <channel>
+    <title>{{ site.title | xml_escape }}</title>
+    <description>{{ site.description | xml_escape }}</description>
+    <link>{{ site.url }}{{ site.baseurl }}/</link>
+    <atom:link href="{{ "/feed/index.xml" | absolute_url }}" rel="self" type="application/rss+xml"/>
+    <pubDate>{{ site.time | date_to_rfc822 }}</pubDate>
+    <lastBuildDate>{{ site.time | date_to_rfc822 }}</lastBuildDate>
+    <generator>Jekyll v{{ jekyll.version }}</generator>
+    {% for post in site.posts limit: 15 %}
+      {% unless post.draft %}
+        <item>
+          {% if post.title != "" %}
+            <title>{{ post.title | xml_escape }}</title>
+          {% endif %}
+          <author>{{ site.email }} ({{ site.title }})</author>
+          <description>
+            {{ post.content | xml_escape }}
+          </description>
+          <pubDate>{{ post.date | date_to_rfc822 }}</pubDate>
+          <link>{{ post.url | absolute_url }}</link>
+          <guid isPermaLink="true">{{ post.url | absolute_url }}</guid>
+          {% for tag in post.tags %}
+          <category>{{ tag | xml_escape }}</category>
+          {% endfor %}
+          {% for cat in post.categories %}
+          <category>{{ cat | xml_escape }}</category>
+          {% endfor %}
+        </item>
+      {% endunless %}
+    {% endfor %}
+  </channel>
+</rss>