code style.

Signed-off-by: Jack <jack.wgm@gmail.com>
improve cookie parser, use boost::to_lower_copy.

Signed-off-by: Jack <jack.wgm@gmail.com>
add calc Content-Length for file_upload.

Signed-off-by: Jack <jack.wgm@gmail.com>
improve calc_content_length.

Signed-off-by: Jack <jack.wgm@gmail.com>