Implement more embed code

Supported Media Files:
- Youtube
- Vimeo
- Instagram
- Flickr
- Slidershare
- Speakerdeck

close #26

db/migrate/20140319143547_rename_video_to_media_on_events.rb

@@ -0,0 +1,11 @@
+class RenameVideoToMediaOnEvents < ActiveRecord::Migration
+  def up
+    rename_column :events, :video_id, :media_id
+    rename_column :events, :video_type, :media_type
+  end
+
+  def down
+    rename_column :events, :media_id, :video_id
+    rename_column :events, :media_type, :video_type
+  end
+end