Add missing namespace to @covers comments

Add missing namespace to @covers comments

PHP_CodeCoverage_Exception:
> Trying to @cover not existing method "SwiftFileBackend::sanitzeHdrs".
> Trying to @cover not existing method "LineFormatter::normalizeException".
> Trying to @cover not existing method "MonologSpi::mergeConfig".
> Trying to @cover not existing method "ProcessCacheLRU::het".
> Trying to @cover not existing method "BitmapHandler::swapICCProfile".
> Trying to @cover not existing class or interface "checkParseSafety".
> Trying to @cover not existing method "Article::__call". (was removed).
> Trying to @cover not existing method "ExtensionProcessor::extracttExtensionMessagesFiles".
> Trying to @cover not existing method "FileContentsHasher::getFileContentHash".

Makes code coverage run fail at the moment. These used to be warnings
in PHPUnit 3.x, but are now hard exceptions in PHPUnit 4.x when requesting
a coverage report.

Change-Id: If7f45ca57fd7d480d35b1414a889398837c0c472