I18n/topic tree

Let's support i18n for the cool Topic feature!

![topics_english](https://cloud.githubusercontent.com/assets/514294/5351583/77910726-7f9b-11e4-8971-ffcb1ea1e906.png)
*Multibyte Topic name and topic category name*

![allow_multibyte_topic_node](https://cloud.githubusercontent.com/assets/514294/5351580/6a9f3452-7f9b-11e4-9665-3a8eae616265.png)
*Multibyte Topic name*

![treat_spaces_as_hyphens](https://cloud.githubusercontent.com/assets/514294/5351610/dc81e0e2-7f9b-11e4-8ba9-2de1f89ac7e2.png)
*Strip white spaces and treats spaces as hyphens*

![xss](https://cloud.githubusercontent.com/assets/514294/5351620/20179acc-7f9c-11e4-8ac4-a5ff727209b8.png)
![xss1](https://cloud.githubusercontent.com/assets/514294/5351621/22156372-7f9c-11e4-97f0-54ff3464e7d8.png)
*Sanitize scripts*

![blog_english](https://cloud.githubusercontent.com/assets/514294/5351628/40a12baa-7f9c-11e4-9384-b6b2ea90d080.png)
![urlencode_topic_name](https://cloud.githubusercontent.com/assets/514294/5351617/04688bf6-7f9c-11e4-8579-461908e2cd92.png)
*In front-end, topic names are url encoded*

![blog](https://cloud.githubusercontent.com/assets/514294/5351631/4d107c7e-7f9c-11e4-8153-664b5ba83984.png)
![i18n_topic_node](https://cloud.githubusercontent.com/assets/514294/5351641/6bccc06e-7f9c-11e4-9542-c5c47e8ab59d.png)
*Then we can display translated topic node name!*