Merge branch 'release-0.40.0' into develop

* release-0.40.0:
  Bumping version to 0.40.0
Fix sdb endpoint for us-east-1
Fix bucket leaks in integ tests

The integ tests for S3 weren't cleaning up buckets properly.
Verified that now all buckets are properly deleted.
Merge branch 'no-leak-bucket-test' into develop

* no-leak-bucket-test:
  Fix bucket leaks in integ tests
Fix kinesis pagination issue

Add support for non_aggregate_keys in the pagination
configs.

Also went through the other kinesis paginated operations
and verified that DescribeStream is the only thing that
needs non_aggregate_keys.

Fixes #270.
Only add existing value if search is not None
Merge branch 'kinesis-pagination' into develop

* kinesis-pagination:
  Only add existing value if search is not None
  Fix kinesis pagination issue
Update docs for s3 storage class
Merge branch 's3-storage-class' into develop

* s3-storage-class:
  Update docs for s3 storage class
Bumping version to 0.41.0
Merge branch 'release-0.41.0'

* release-0.41.0:
  Bumping version to 0.41.0
  Update docs for s3 storage class
  Only add existing value if search is not None
  Fix kinesis pagination issue
  Fix bucket leaks in integ tests
  Fix sdb endpoint for us-east-1