Merge pull request #56 from pkit/minor_fixes

changed SwiftPath to better support various URLs
fixed bad behavior when rewriting output

In case where output device has `Content-Type` : `message/cgi` or 'message/http` and it's a `WRITABLE` device and it is a local device the file needs to be rewritten on disk

Why?

Because if it's a writeble local file it will be relocated to be an object in-place and then we need to delete all the `message` headers from it. Headers are only needed when such object is sent back over HTTP, but not when it's stored.
To rewrite such object we used mkstemp() which creates a file in `/tmp` by default. But according to Swift rename rules temp object must be on the same device as the intended real object.
This patch uses mkstemp(dir=swift_temp_dir) which places the temp files in a correct dir
Merge pull request #57 from pkit/object_fixes

fixed bad behavior when rewriting output
refactor config variables in middlewares

optimized load of the config files in proxyquery and objectquery
now both of them will load some vars from corresponding server config (proxy-server or object-server)
it should avoid duplicating vars for both middleware section and server section
move retcode_map to module level constant