Move bmcweb over to sdbusplus

This patchset moves bmcweb from using boost-dbus over entirely to
sdbusplus.  This has some nice improvements in performance (about 30%
of CPU cycles saved in dbus transactions), as well as makes this
project manuver closer to the upstream way of thinking.

Changes to bmcweb are largely ceremonial, and fall into a few
categories:
1. Moves async_method_call instances to the new format, and deletes any
use of the "endpoint" object in leiu of the sdbusplus style interface
2. sdbus object_path object doesn't allow access to the string
directly, so code that uses it moves to explicit casts.
3. The mapbox variant, while attempting to recreate boost::variant,
misses a T* get<T*>() method implementation, which allows using variant
without exceptions.  Currently, there is an overload for
mapbox::get_ptr implementation which replecates the functionality.

Tested by: Booting the bmcweb on a target, iterating through redfish
basic phosphor-webui usage, and websockets usage

Change-Id: I2d95882908d6eb6dba00b9219a221dd96449ca7b
Signed-off-by: Ed Tanous <ed.tanous@intel.com>
diff --git a/src/webserver_main.cpp b/src/webserver_main.cpp
index 16180ae..7531503 100644
--- a/src/webserver_main.cpp
+++ b/src/webserver_main.cpp
@@ -1,11 +1,13 @@
 #include <systemd/sd-daemon.h>
-#include <dbus/connection.hpp>
 #include <dbus_monitor.hpp>
 #include <dbus_singleton.hpp>
 #include <intel_oem.hpp>
 #include <openbmc_dbus_rest.hpp>
 #include <persistent_data_middleware.hpp>
 #include <redfish_v1.hpp>
+#include <sdbusplus/asio/connection.hpp>
+#include <sdbusplus/bus.hpp>
+#include <sdbusplus/server.hpp>
 #include <security_headers_middleware.hpp>
 #include <ssl_key_handler.hpp>
 #include <token_authorization_middleware.hpp>
@@ -73,12 +75,11 @@
   CROW_LOG_INFO << "bmcweb (" << __DATE__ << ": " << __TIME__ << ')';
   setup_socket(app);
 
-  // Start dbus connection
   crow::connections::system_bus =
-      std::make_shared<dbus::connection>(*io, dbus::bus::system);
-
+      std::make_shared<sdbusplus::asio::connection>(*io);
   redfish::RedfishService redfish(app);
 
   app.run();
   io->run();
+
 }