Merge pull request #65 from hermanschaaf/master

Small bugfix and decanter version bump to 0.1.6.5
Simplify Singleton and Config

Config original did not work in Python3.x, but this works.
But do not work in Python3.x If do not rewritten others too.
Ensure compatibility
add tests
Merge pull request #66 from narusemotoki/develop

Simplify Singleton and Config
BUG-904 make sure redis connection is returned to the pool (closed) after each request + minor formatting fix
BUG-904 add close method to abstract session class
Merge pull request #67 from gengo/BUG-904-fix-closing-session

BUG-904 fix closing session