Add support for searching and rendering bhajans from remote database.

- Support MongoHQ database connection.
- Add 404 placeholder and route missing bhajans to 404 view.
- Add individual bhajan Jade view with title, lyrics, and translation.
- Add search results Jade view to list matched bhajans.
- Add search input & button to homepage.
- Search lyrics instead of title. Sort search results by title.
- Configure Travis with encrypted database credentials.
- Allow Travis build failures for old and beta versions of node.