Add SQLite support

[rognoni]

For my project I'm using SQLite instead of MySQL: https://docs.python.org/3/library/sqlite3.html

[2shou]

could you give me a PR?

[rognoni]

(I have not PR for the moment, this is only an improvement request)

For example this is a work-in-progress using SQLAlchemy (I'm looking for good alternatives about ORMs) https://github.com/rognoni/adaptable/blob/master/Backend/Python-Flask/storage/sqlalchemy_sqlite.py

For the moment I have only these ORMs to test: http://pythoncentral.io/sqlalchemy-vs-orms/