remove swift dependency of s3 middleware
remove swift dependency of s3 middleware

In middleware/s3_token.py, here only use swift for a logger and path
split functionality. We should remove swift dependency by using new
codes.

fixes bug #1178738

Change-Id: Icc2648720e220a873d1fb8e9961d777ceabef70b

varunarya10/keystonemiddleware