Fix issue when error response is receieved for streaming output

Fixes the second half of #1006.  Now you'll get a proper error
message:

```
$ aws s3api get-object --bucket b --key k /tmp/outfile

A client error (InvalidRequest) occurred when calling the GetObject
operation: The object was stored using a form of Server Side Encryption.
The correct parameters must be provided to retrieve the object.

```

Closes #1006.
Add 1012 to the CHANGELOG
Merge branch 'streaming-output-arg' into develop

* streaming-output-arg:
  Add 1012 to the CHANGELOG
  Fix issue when error response is receieved for streaming output

Conflicts:
	CHANGELOG.rst