Fixes NPE when return types are void

fixes #130, #139, #146
[maven-release-plugin] prepare release swagger-springmvc-0.6.5
[maven-release-plugin] prepare for next development iteration
Updated the documentation to 0.6.5
Merging from rel-0.6
Tests that exercise the documentation APIs for a class that inherits its RequestMappings from an interface
Added some sensible ignores
Support documentation APIs for a class that inherits its RequestMappings from an interface
Update readme.md
Merge pull request #158 from sverhagen/master

Fix for when the RequestMapping(s) are declared on interfaces that the controller inherits