Update python sdk examples to use new method names

[danielhelfand]

• customers_api.delete -> customers_api.delete_customer
• result.success -> result.is_success
• result.error -> result.is_error
• customers_api.list() -> customers_api.list_customers()

[zenmasterjobo]

Hi @danielhelfand

Thanks for bringing this up! We have actually decided to remove the examples directory for now. Because of that I will be closing this PR.

Thanks again!