Dynamically generate cors rules, fixes #22

[Makeshift]

what

• We now dynamically generate the cors rules block so we correctly create a block for each alias/allowed origin.

why

• Cors origins don't work without these changes
• I believe this change makes them work as intended in the original module

references

• Close Bug in configuration of allowed origins for S3 bucket #22
• I hit enter too early, sorry for the edits :)

[osterman]

/test all

[osterman]

Unfortunately tests are failing b/c someone's tests have created the bucket and not deleted it. We'll need to fix the tests in this module before merging by generating the bucket name.

If you are able to incorporate these changes, that would be much appreciated. See example here: https://github.com/cloudposse/terraform-aws-alb/pull/42/files

[Gowiem]

/test all

[Gowiem]

@Makeshift Thanks for the contribution! Released as 0.24.0.