add oauth callback url

change gem source to rubygems; config db url

add vendors and move sqlite to development group

add sqlite back

try remove sqlite again..

change Gemfile accordingly
use postgres even in test and development
add bin dir in; move bin out of .gitignore
register, login, logout
if not connected with douban yet, ask user to
show existing groups and be able to create new ones
be able to join/leave group
show how many people read; show which one you've read