* updated keywords in metainfo.html
* added 'baidu-site-verification' to metainfo.html
* enabled 'south' in 'INSTALLED_APPS'
* added 'introspection_rules' of ContentTypeRestrictedFileField for south
* added 'is_checkin' field to account.models.UserProfile
* added 'get_checkin_value', 'dump_fieldnames' and 'dump' methods to UserProfile model
* generated south migrations for app 'account'
* display two more columns (email, is_checkin) in UserProfileAdmin
* added 'get_urls' and 'userprofile_csv_view' to UserProfileAdmin
* updaed 'profile.html' with 'is_checkin' field
small updates to account/models.py