Quote the filename in the x-amz-copy-source header for multipart COPY operations.  Fixes #614.
Let botocore handle the quoting of the x-amz-copy-source header.
The fake session should no longer unquote the copy_source.
Don't encode the copy_source argument

Picks up on where #615 left off.
Update CHANGELOG
Merge branch 'garnaat-fix-614' into develop

* garnaat-fix-614:
  Update CHANGELOG
  Don't encode the copy_source argument
  The fake session should no longer unquote the copy_source.
  Let botocore handle the quoting of the x-amz-copy-source header.
  Quote the filename in the x-amz-copy-source header for multipart COPY operations.  Fixes #614.

Conflicts:
	CHANGELOG.rst