SES API was only showing 1 out of 3 DKIM Tokens. Fixed by adding DkimTokens to list_markers.

I was using boto with the SES API in concert with the Route53 API and was puzzled that the SES API only provided one out of the 3 required DKIM tokens. I assumed that only 1 was needed and went ahead and used it but this proved to be incorrect. I found that adding DkimTokens to the list_markers item in the `SES._make_connection()` method fixed the issue.

I know that the CONTRIBUTING file specifies that it should include tests but I don't see any tests for SES.