快merge，混蛋！

表示发现有bug（见下面的第二条）就改了下，改完之后发现代码根本就彻底重写了一遍……
现在点击“加载更多”之后还是不会给新加载出来的项目加上“不喜欢”按键。= =

1. now the script works only for the main page; even "douban.com/#" will also be included;
2. the dislike button will only show for *items*.
3. reuse css provided by douban
4. refactored the code...