fix a bug where :view_paths wouldn't be inherited to nested helpers. added a stronger test.
Merge pull request #553 from apotonick/views-prefix

Fix a bug where :view_paths wouldn't be inherited to nested helpers.
Fix wrong travis config
Use padrino helpers ~> 0.11.0 if Ruby version is 1.8.7
Try using minitest on rbx instead of rubysl-test-unit