Added a check for the OK file upload code to avoid checking all the
alternatives when the upload was ok.
Return from the method in the file size error branch when the file was
not uploaded.
Added a check in the MIME type validation to only check MIME types if
the CUploadedFile's tempName is not empty.
Updated CHANGELOG
Updated CHANGELOG
Merge pull request #2790 from Rupert-RR/#2778_BUG_CFileValidator_General_exception_when_validating_MIME_types_for_file_whose_upload_failed_due_to_file_size

#2778 Bug - CFileValidator general exception when validating mime types for file whose upload failed