Improve test coverage of Middleware
Improve test coverage of Middleware

- Ensure it returns identical objects from decorate{Request,Response} if
  they are already decorated.

matwright/zend-stratigility,Diego-Brocanelli/zend-stratigility,xtreamwayz/zend-stratigility,jguittard/zend-stratigility,liuggio/zend-stratigility,Maks3w/zend-stratigility,codeliner/zend-stratigility