* added contents for 'accommodation', 'committee', 'sponsor' and 'traffic' pages
* installed 'django-recaptcha'
* added 'captcha' field to UserRegForm
* deleted 'Notice.publisher' field
* added 'blank=True' to 'NoticeAttachment.description' field
* fixed attachment issue with 'list_notice.html' template
* added 'django-recaptcha' settings
* added 'ALLOWED_CONTENT_TYPES' to settings
* updated 'settings_mysql' and 'settings_production'
* implemented 'password_reset' function based on django auth views
* added password_reset related templates and email templates
* updated account urls.py
* updated ALLOWED_CONTENT_TYPES
* implemented ContentTypeRestrictedFileField based on FileField
* updated 'profile_update' template:
  o account_profile_update.css account_profile_update.js
  o added fields 'reason', 'transcript', 'supplement'
  o supported upload files (optional, dynamical formset)
* updated urls.py of 'password_reset' view
* added model 'UserFile' and register to admin
* updated 'UserProfile' model:
  o added fields 'reason', 'transcript', 'supplement'
  o used 'ContentTypeRestrictedFileField' with dynamical 'upload_to'
* updated 'UpdateProfileView' to support formset
* updated 'UpdateProfileForm' with new fields and clean method
* added 'UserFileForm' and 'UserFileFormSet'
* added 'OverwriteStorage()' to overwrite previous uploaded files
* overwrite 'save' method to delete previous uploaded files