tests improved, verify added
beforeSubmit function after global validation all fields forms
Renames AccessDeniedHttpException to ForbiddenHttpException as in #2103
Deletes AccessDeniedHttpException
Adds UnauthorizedHttpException class for 401 errors
Adds GoneHttpException for 410 http errors
Adds NotAcceptableHttpException for 406 Http errors
Adds ConflictHttpException for 409 http errors
Adds TooManyRequestsHttpException for 429 http errors
Adds UnsupportedMediaTypeHttpException for 415 Http errors
Renames AccessDeniedHttpException to ForbiddenHttpException in framework, docs, and extension files
updated apidoc composer.json

require a version that contains phpDocumentor/Reflection#16
Added ability to get incoming headers
added basic greek translation
added Greek (el) as available language
Merge branch 'master' of git://github.com/yiisoft/yii2 into get-headers
removed unnecessary greek translations from core
fixed paths in apidoc script according to psr-4 autoload and composer/bin
Minor fixes in active-record.md
Merge pull request #2112 from crtlib/patch-4

Minor fixes in active-record.md