Add https:// prefix to event feed link urls
Add https:// prefix to event feed link urls

fixes #916 on github

azavea/nyc-trees,kdeloach/nyc-trees,maurizi/nyc-trees,azavea/nyc-trees,kdeloach/nyc-trees,azavea/nyc-trees,maurizi/nyc-trees,azavea/nyc-trees,maurizi/nyc-trees,kdeloach/nyc-trees,azavea/nyc-trees,kdeloach/nyc-trees,kdeloach/nyc-trees,maurizi/nyc-trees