Update version number to 3.8.0-RC3
Update version number to 3.8.0-RC3

ndm2/cakephp,dakota/cakephp,ndm2/cakephp,CakeDC/cakephp,cakephp/cakephp,mvdriel/cakephp,ndm2/cakephp,CakeDC/cakephp,cakephp/cakephp,ADmad/cakephp,ndm2/cakephp,ADmad/cakephp,ADmad/cakephp,cakephp/cakephp,mvdriel/cakephp,dakota/cakephp,cakephp/cakephp,CakeDC/cakephp,mvdriel/cakephp,dakota/cakephp,dakota/cakephp,ADmad/cakephp,CakeDC/cakephp,mvdriel/cakephp