Make the request accept */* when HTTP_ACCEPT is not present or blank
According to https://github.com/slim-template/slim/blob/master/CHANGES
`attr_wrapper` has been renamed to `attr_quote`

Fix slim tests to handle this change
Merge pull request #768 from patriciomacadden/accept

Make the request accept */* when HTTP_ACCEPT is not present or blank
Merge pull request #767 from vipulnsward/change_attr_wrapper

`attr_wrapper` => `attr_quote`