* Splited storage function from account.extra -> tools/storage.py
  - OverwriteStorage
  - file_cleanup
* Updated account.models, archive.models
* Added OverwriteStorage and file_cleanup function to notice.models

* updated profile.html to show 'sjtu_id' and 'sjtu_initpass' info
  and show a related alert
* updated zh_CN locale messages

* added fields 'sjtu_id' & 'sjtu_initpass' to UserProfile model
* updated 'dump()' and 'dump_fieldnames()' method
* updated 'UserProfileAdmin' to show these fields
* added south migration 0004 for newly added two fields

* displayed one more column 'id'
* added filter function
* changed display style of 'is_approved', 'is_sponsored' and
  'is_checkin': display icons instead of text

* validate username with regex on registration (bootstrap3 frontent does
  not handle regex correctly. XXX) -> account/forms.py
* small update to registration page title display style

* changed 'identify' to 'identity' in Model 'UserProfile'
* updated forms.py, admin.py, profile.html related to 'identity'
* added South migration for renaming field 'identify' to 'identity'
* updated display contents of 'list_approved': removed 'identity' column
* updated 'institute' field name to 'institute (and major)'
* updated related translations

* added 'account/csv_unicode.py' to provide Unicode CSV I/O support
* used 'UnicodeWriter' in 'account/admin.py' userprofile_csv_view to generate csv format export

* 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