Fix s3 event race condition bug

[pmuens]

What did you implement:

Closes #3038

Fixes the race condition bug where S3 events randomly fail while deploying the service.

How did you implement it:

Added a DependsOn declaration which contains the buckets permission. This ensures that the permission is in place before the bucket is created.

How can we verify it:

Just deploy a service like the following:

service: service

provider:
  name: aws
  runtime: nodejs6.10

functions:
  hello:
    handler: handler.hello
    events:
      - s3: some.random.bucket.name

or run the S3 (complex) integration tests. They should stop failing now.

Todos:

• Write tests
• Fix linting errors
• Make sure code coverage hasn't dropped
• Provide verification config / commands / resources
• Update the messages below

Is this ready for review?: YES
Is it a breaking change?: NO

[eahefnawy]

Works! G2M 👍