Method support

Add support for a method callback.  The method callback enables
arbitrary DBus method calls.  A sample use case could be
starting a systemd unit via the sytemd DBus API.

Change-Id: If25131d11497c82f862ae1f47da066c5fd8b2e2e
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/src/templates/method.mako.cpp b/src/templates/method.mako.cpp
new file mode 100644
index 0000000..31cdf65
--- /dev/null
+++ b/src/templates/method.mako.cpp
@@ -0,0 +1,6 @@
+makeMethod<SDBusPlus>(
+${indent(1)}ConfigInterfaces::get()[${c.service}],
+${indent(1)}ConfigPaths::get()[${c.path}],
+${indent(1)}ConfigInterfaces::get()[${c.interface}],
+${indent(1)}ConfigProperties::get()[${c.method}],
+${indent(1)}${(',\n' + indent(1)).join([val.argument(loader, indent=indent +1) for val in c.args])})\