migrate default verstion to v7.0

[tranvansang]

Facebook API v3 will stop working from July 28, 2020 (1 month from now)

https://developers.facebook.com/docs/graph-api/changelog

** READ THIS FIRST! **

Are you implementing a new feature?

no

Is this a security patch?

no

Checklist

• I have read the CONTRIBUTING guidelines.
• I have added test cases which verify the correct operation of this feature or patch.
• I have added documentation pertaining to this feature or patch.
• The automated test suite ($ make test) executes successfully.
• The automated code linting ($ make lint) executes successfully.

➜ passport-facebook git:(patch-1) make lint
make: *** No rule to make target 'lint'. Stop.