Revert "Corrected the default response format"

This reverts commit 7eb323f9ec5b6794fbd4adfc5a768352e6069103.
Revert "Assert content-type header for all HEAD requests"

This reverts commit 6bcaa9b569488687b84e7791a2a0748be51ce385.
Tweaked the response format handling in the controller to work better.