Should respect content-type or 406 the ones not supported.

[xadhoom]

Right now the saas always return the content-type as application/json, even when the client does not support it.

If application/json is the only content-type supported, the service should answer 406 Not Acceptable when application/json is not in the Accept headers, OR provide a valid representation of the resources according to the Accept headers.

Which basically means it should return an html or text page if the client accepts only text/html or text/plain. Obviously all the others content types should be refused with a 406.