* Add buttons to show/hide results from Douban & Google
* Trigger search with "Enter" key
* Use Underscore.js template instead of build HTML strings in JavaScript
* Keep click event handler in JavaScript instead of using HTML's `onclick`
* Normalize Douban & Google results
* Update cover image & add cover URL to the form input
Added ability to reload database connection (refresh problem)
Bugfix display hot books (no hot books, hot books are deleted books, no longer result in error 500)