add an error page, when something unexpected happened (via exception), go to error page
add an empty file to put stuffs concerned with Tongji Library
output raw texts to a book paper block
display user's information on the right of header
change the search input box of nav sidebar to be type="search"
change the search box to redirect to google
now the active nav item is highlighted (has an orange sign)
the /me page now displays in the nav framework
add a hint to the "See what is in there" link in NO SUCH BOOK in RANDOM!
when user is not connected with douban, the information on the right of header would be lower
after login or signup, redirect to /me
change the color representing 'current page' in nav bar
show a "encourage to bind douban" msg when not connected; reconstruct a function in less files files
when oauth2 of douban fails, goto error page and say why
now it can show douban information when it's connected
Merge branch 'server'