Allow user-specified Model base classes.
Merge branch 'master' into custom-model-base-class

* master:
  Honor SQLALCHEMY_RECORD_QUERIES even in debug mode.
  Scoped Session returns instance object.
  Let the user pass keyword arguments to the 'create_engine'.
  Allow optional message on 404 from db query

Conflicts:
	flask_sqlalchemy/__init__.py
Merge branch 'master' into custom-model-base-class

* master:
  Honor SQLALCHEMY_RECORD_QUERIES even in debug mode.
  Scoped Session returns instance object.
  Let the user pass keyword arguments to the 'create_engine'.
  Allow optional message on 404 from db query

Conflicts:
	flask_sqlalchemy/__init__.py
Merge pull request #5 from EchoGlobalLogistics/custom-model-base-class

Allow user-specified Model base classes.