Merge pull request #5 from pbl-cloud/wrapup

リファクタリング・モジュール化・機能追加
Update README.md.
Small refactoring and functionality add in database_connector.py.
Use more generic methods for database accesses.
Fix bug in object hydration.
Handle login/logout properly.
Fix models.
Fix validation.
Remove done TODO.
Fix views.py.
Move logic out from views.py.
Change queue manager to update stdout and stderr.
Remove unused methods and upate tests.