add python3 support

.travis.yml

README.md

dev_requirements.txt

docs/conf.py

docs/index.rst

examples/basic_auth/app.py

examples/basic_auth/app_oldap.py

examples/blueprints/blueprints/extensions.py

examples/groups/app.py

examples/groups/app_oldap.py

flask_simpleldap/__init__.py

requirements.txt

setup.py