[AWS|Core] add eu-central-1 to the region whitelist
[AWS|Compute] switch to signature version 4
[AWS|Signature] make signature v4 components easy to extract
[AWS|Signature] V4 parameter signature needs to add X-Amz-Credential etc. before signing
[AWS|S3] switch to signature v4
[AWS|IAM] Use signature version 4
[AWS|ELB] Use Signature v4
[AWS|ELB] Update list of regions the mocks allow
[AWS|RDS] Use Signature v4
[AWS|RDS] update list of regions accepted by mocks
[AWS|Cloudwatch] Use Signature v4
[AWS|Cloudwatch] Update list of regions allowed by the mock
[AWS|Autoscaling] Use Signature v4
[AWS|Autoscaling] Update list of regions accepted by the mocks
[AWS|Elasticache] Use Signature v4
[AWS|STS] Use Signature v4
[AWS|SNS] Use Signature v4
[AWS|SQS] Use Signature v4
[AWS|SQS] Update list of regions allowed by mocks
[AWS|CloudFormation] Use Signature v4