message: Fix inconsistent RFC1123 date format in different system locales
diff: #include "common/common_headers_request_policy.hpp"
  #include <ctime>
  +#include <iomanip>
  +#include <sstream>
  namespace Azure { namespace Storage {
  @@ -27,9 +29,10 @@ namespace Azure { namespace Storage {
  #else
  gmtime_r(&t, &ct);
  #endif
  - char dateString[128];
  - strftime(dateString, sizeof(dateString), "%a, %d %b %Y %H:%M:%S GMT", &ct);
  - request.AddHeader(c_HttpHeaderXMsDate, dateString);
  + std::stringstream dateString;
  + dateString.imbue(std::locale("C"));
  + dateString << std::put_time(&ct, "%a, %d %b %Y %H:%M:%S GMT");
  + request.AddHeader(c_HttpHeaderXMsDate, dateString.str());
  }
  return nextHttpPolicy.Send(ctx, request);
  