resolves #8 add JSON feed

feed.json

@@ -0,0 +1,32 @@
+---
+layout: null
+---
+{
+    "version": "https://jsonfeed.org/version/1",
+    "title": "{{ site.title | xml_escape }}",
+    "home_page_url": "{{ site.baseurl | absolute_url }}",
+    "feed_url": "{{ "/feed/index.json" | absolute_url }}",
+    "description": {{ site.description | jsonify }},
+    "icon": "{{ site.icon | absolute_url }}",
+    "favicon": "{{ "/favicon.ico" | absolute_url }}",
+    "expired": false,
+    "items": [
+    {% for post in site.posts limit: 15 %}
+      {% unless post.draft %}
+        {% capture content_text %}{{ post.content | strip_html }}{% endcapture %}
+        {% capture content_html %}{{ post.content | markdownify }}{% endcapture %}
+        {
+            "id": "{{ post.url | absolute_url | sha1 }}",
+            {% if post.title != "" %}"title": {{ post.title | jsonify }},{% endif %}
+            "content_text": {{ content_text | jsonify }},
+            "content_html": {{ content_html | jsonify }},
+            "url": "{{ post.url | absolute_url}}",
+            "date_published": "{{ post.date | date_to_xmlschema }}",
+            "date_modified": "{{ post.date | date_to_xmlschema }}",
+            "author": {
+                "name": "{{ post.author }}"
+            }
+        {% endunless %}
+    {% endfor %}
+    ]
+}