http_request and http_response doesn't satisfy the rule of five

[evilenzo]

As you can see in https://github.com/microsoft/cpprestsdk/blob/master/Release/include/cpprest/http_msg.h http_request and http_response don't satisfy the rule of five and also have a non-trivial destructor. So no move will work on this types what is actually sad

[evilenzo]

Pull Request: https://github.com/microsoft/cpprestsdk/pull/1668