Converts a string to the request method verb.
Defined in header <beast/http/verb.hpp>
If the string does not match a known request method, http::unknown is returned.
Convenience header <beast/http.hpp>
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)