Add sbusplus properties server

Add properties server similar to boost-dbus that allows
for creating dbus interfaces during runtime. This adds
support for creating methods and get / set properties.

Get / set property callbacks are stored in flat_maps of
std::function allowing custom get / set functions. Methods
are also stored in this way allowing for creating of interfaces
without using any yaml. There is one C level callback for properties
get, properties set, and method calls that lookup the correct
std::function in the flat_map to call.

Tested: Ran asio-example on bmc, and updated fru-device.
Change-Id: I19881049f4307fe9c68f78df8854f14afdd6c362
Signed-off-by: James Feist <james.feist@linux.intel.com>
diff --git a/Makefile.am b/Makefile.am
index 94a88f6..533f423 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -6,6 +6,7 @@
 	mapbox/recursive_wrapper.hpp \
 	mapbox/variant.hpp \
 	sdbusplus/asio/connection.hpp \
+	sdbusplus/asio/object_server.hpp \
 	sdbusplus/asio/detail/async_send_handler.hpp \
 	sdbusplus/bus.hpp \
 	sdbusplus/bus/match.hpp \