Refactoring part 1

Some changes for workers, but stopped due to refactoring

common/extensions.py

@@ -0,0 +1,17 @@
+from flask_sqlalchemy import SQLAlchemy
+from flask_migrate import Migrate
+from flask_bootstrap import Bootstrap
+from flask_security import Security
+from flask_mailman import Mail
+from flask_login import LoginManager
+from flask_cors import CORS
+
+
+# Create extensions
+db = SQLAlchemy()
+migrate = Migrate()
+bootstrap = Bootstrap()
+security = Security()
+mail = Mail()
+login_manager = LoginManager()
+cors = CORS()