CS fixes
Merge pull request #1285 from dereuromark/master-cs-fixes

CS fixes
The assembly of the message was not correctly completed in specific Japanese.
Add TestCase for Network/Email/CakeEmail.php
code is not translatable and should not be part of the translation strings
Merge pull request #1287 from dereuromark/master-translation-strings

code is not translatable and should not be part of translation strings
Merge pull request #1286 from kunit/master

CakeEmail::_wrap does not operate correctly by the character string of specific Japanese.
Fix empty response bodies when redirect URL's are empty.

When redirecting XHR requests to an empty URL the response body should
not be overwritten.

Fixes #3835
Fix incorrect exception type when double slash paths are used.

Fixes #3838
Merge branch 'master' into 2.4