sort category posts by time
Add pagination for posts display

Add pagination for category posts

Improve UI of category index page
remove user index page
only display pagination if there are > 1 pages
Add pagination to category show page
Update README.md
update category record name
minify javascript
add avatar_url func and use v2ex gravatar cdn
don't display post button on sidebard if user is logged out
Merge pull request #21 from lidashuang/master

add avatar_url and use v2ex gravatar cdn
Add mention `@` notification
Add a space after mention link
Temporary remove posts by user id
Update README.md
Update README.md
Add contribution section to README.md
Add user ranking and forum stat to category pags
fix typo
enlarge brand size