Add test for accept header.
Add test for accept header.

Refs #2828

mvdriel/cakephp,erikfig/cakephp,CakeDC/cakephp,burriko/cakephp,eryw/cakephp,eryw/cakephp,cakephp/cakephp,justinyost/cakephp,CVO-Technologies/cakephp,nrother/cakephp,eboominathan/cakephp,Balachan27/cakephp,dkarvounaris/cakephp,pbaire/cakephp,thinkingmedia/cakephp,eboominathan/cakephp,web-player/cakephp,pbaire/cakephp,dakota/cakephp,bravo-kernel/cakephp,elboletaire/cakephp,tisu2tisu/cakephp,petteyg/cakephp,elboletaire/cakephp,Balachan27/cakephp,adopico/cakephp,dakota/cakephp,tenkoma/cakephp,mvdriel/cakephp,tenkoma/cakephp,timhoeppner/cakephp,tgr0ss/cakephp,ndm2/cakephp,garethellis36/cakephp,khoimt/cakephp-study,burriko/cakephp,kumamidori/cakephp,michaelze/cakephp,jjj117/cakephp,CakeDC/cakephp,khoimt/cakephp-study,berrygoudswaard/cakephp,eboominathan/cakephp,jeffblack360/cakephp,nrother/cakephp,web-player/cakephp,ndm2/cakephp,et304383/passbolt_api,ionas/cakephp,khoimt/cakephp-study,davidyell/cakephp,nrother/cakephp,burriko/cakephp,HavokInspiration/cakephp,CVO-Technologies/cakephp,tisu2tisu/cakephp,jjj117/cakephp,yinhe007/cakephp,pbaire/cakephp,web-player/cakephp,et304383/passbolt_api,tgr0ss/cakephp,ndm2/cakephp,timhoeppner/cakephp,justinyost/cakephp,cakephp-fr/cakephp,jerems02/cakephp,garethellis36/cakephp,dkarvounaris/cakephp,jeffblack360/cakephp,bravo-kernel/cakephp,jeffblack360/cakephp,petteyg/cakephp,cakephp/cakephp,dakota/cakephp,erikfig/cakephp,Balachan27/cakephp,erikfig/cakephp,garethellis36/cakephp,ndm2/cakephp,HavokInspiration/cakephp,et304383/passbolt_api,gmponos/cakephp,Phillaf/cakephp,adopico/cakephp,jjj117/cakephp,CakeDC/cakephp,gmponos/cakephp,akintoey/cakephp,ADmad/cakephp,thinkingmedia/cakephp,et304383/passbolt_api,akintoey/cakephp,petteyg/cakephp,davidyell/cakephp,ADmad/cakephp,elboletaire/cakephp,cakephp/cakephp,adopico/cakephp,dkarvounaris/cakephp,yinhe007/cakephp,michaelze/cakephp,yinhe007/cakephp,michaelze/cakephp,gmponos/cakephp,ionas/cakephp,tgr0ss/cakephp,tenkoma/cakephp,mvdriel/cakephp,et304383/passbolt_api,timhoeppner/cakephp,HavokInspiration/cakephp,CVO-Technologies/cakephp,thinkingmedia/cakephp,Phillaf/cakephp,kumamidori/cakephp,CakeDC/cakephp,ionas/cakephp,berrygoudswaard/cakephp,ADmad/cakephp,kumamidori/cakephp,cakephp-fr/cakephp,ADmad/cakephp,berrygoudswaard/cakephp,akintoey/cakephp,justinyost/cakephp,jerems02/cakephp,davidyell/cakephp,cakephp/cakephp,dakota/cakephp,garethellis36/cakephp,Phillaf/cakephp,bravo-kernel/cakephp,petteyg/cakephp,jerems02/cakephp,tisu2tisu/cakephp,tenkoma/cakephp,mvdriel/cakephp,eryw/cakephp,cakephp-fr/cakephp