Fixes table borders for gist (#236)

* removes borders in git tables

* adds jekyll-gist plugin

* adds usage example

* fix line ending

* remove jekyll-gist plugin

* remove jekyll-gist gem

* remove gist example

* catch up recent master changes

css/main.css

@@ -737,3 +737,14 @@ color: #f1c40f;
 .icon-red{
   color: #c0392b;
 }
+
+
+/* Fix table border github gist snippets */
+
+.gist, .gist-file table tr {
+  border: unset;
+}
+
+.gist, .gist-file table tr td {
+  border: unset;
+}