[user-role] Select role when add a user / change role at user admin page;
            Limit guest user's operation: can not create group and library.
added sqls for all models

During seafile server setup, it's better to import sqls than running
django "syncdb" command direclty.
[email-notice] use new time format
[user role] bugfix and improvement
[upload-link] can not get upload link when repo access permmision is read-only
[web-api] fix bug when update user account info
Refactor user role
Merge branch 'user-role'
Change simplejson.JSONDecodeError to ValueError
Fix group msg reply notice bug
Merge pull request #248 from imwhatiam/update-account-bug

[web-api] fix bug when update user account info
[file view] redesigned it; [repo] open file in new window
[sysadmin] Fix toggle user status bug
Merge pull request #246 from haiwen/lins-sqls

added sqls for all models
Merge branch 'email-notice-time'
Merge branch 'upload-link'
[user role] hide 'role' in 'add user' form, hide 'role toggle', fixed bug in 'user search'
[file view] don't request for unread notices's num
[repo] improvement for 'file upload'
[repo] fixed file/dir 'select' bug