EC2: Change logic of deleting resources

[klaphi]

This PR changes the logic of deleting resources of the EC2 driver. Without that change security groups and keypairs will stay because the tasks will be skipped.

The tasks Write Molecule instance configs changes the when condition of the block immediately. This will skip the following tasks regardless of their when conditions. Moving the tasks Write Molecule instance configs to the end of the block will execute the cleanup of Security groups and keypairs according to their own when condition.

[klaphi]

This will fix: #280

[apatard]

While the change looks fine (the cleanup should always be done in the end imho), some questions for you:

• I've given a brief look and I'm having hard time to understand how it's solving your issue. Can you please give more details ?
• Which version of molecule are you using ? iirc, the cookiecutter stuff is not used anymore theses days.