Resolved flake8 issues #2343

Review ID: 389001
Merge pull request #14 from priyankarani/feature/task-2343

Resolved flake8 issues #2343
Bump version to 2.6.0.2
Merge branch 'release/2.6.0.2' into develop
Migrate to 2.8 #2343

Review ID: 438001
Merge pull request #16 from priyankarani/develop

Migration to 2.8 #2343
Migrate to 3.0 #3132
Merge pull request #17 from priyankarani/feature/migration

Migration to 3.0 #3132
Bump version to 3.0.1.0
Refactor Checkout

* Remove the inverse dependence on nereid_payment
* Use the payment_gateway modules
* Allow using payment profiles and storing credit card info
Merge pull request #18 from sharoonthomas/develop

Refactor Checkout
Bump version to 3.0.2.0dev1
Fixed flake8 issues
Merge pull request #20 from GauravButola/feature/task-4203

Fixed flake8 issues #4203