Closes#1525
* Adds validation for the `Content-MD5` header.
* If the header value is invalid, the gateway now returns an `InvalidDigest` error.
* If the value is valid but does not match the payload, it returns a `BadDigest` error.
* Adds integration test cases for `PutBucketCors` with `Content-MD5`.
The debuglogger should be a top level module since we expect
all modules within the project to make use of this. If its
hidden in s3api, then contributors are less likely to make
use of this outside of s3api.
Adjusts the admin apis to the new advanced routing changes.
Enables debug logging for the separate admin server(when a separate server is run for the admin apis).
Adds the quiet mode for the separate admin server.