Improve error message for sigv4 and PermanentRedirect errors

The error message now includes a note on specifying the
correct region:
```
 $ aws s3api list-objects --bucket wrong.region.bucket

 A client error (PermanentRedirect) occurred when calling the ListObjects operation:

 The bucket you are attempting to access must be addressed using the specified
 endpoint. Please send all future requests to this endpoint:
 wrong.region.bucket.s3-ap-southeast-2.amazonaws.com
 You can fix this issue by explicity providing the correct region location
 using the --region argument, the AWS_DEFAULT_REGION environment variable, or
 the region variable in the AWS CLI configuration file.  You can get the
 bucket's location by running "aws s3api get-bucket-location --bucket BUCKET".
```

Same thing when you try to access a bucket in eu-central-1.

cc @danielgtaylor @kyleknap 
That's true, it will be the full point, something like, `bucket.s3-us-west-2.amazonaws.com` which could be confusing.  I initially had an additional function that tried to parse the region name from the endpoint, but I was hesitant to add it because it is subject to change and we may not be able to always guarantee we can reliably get the region name.  Do you think it's worth adding that logic to try to print the required region name?