daemon: Some D-Bus API tweaks

Trying to get the Update() method working end-to-end, and figuring out
all the status reporting around it.

src/daemon/org.projectatomic.rpmostree1.xml

@@ -48,7 +48,11 @@
       <arg type="o" name="transaction" direction="out"/>
     </method>
 
+    <!-- Available options:
+         "allow-downgrade" (type 'b')
+    -->
     <method name="Upgrade">
+      <arg type="a{sv}" name="options" direction="in"/>
       <arg type="o" name="transaction" direction="out"/>
     </method>
 
@@ -87,6 +91,17 @@
     <method name="Cancel">
     </method>
 
+    <!-- XXX Blindly mimicing UDisks2.Job for now. -->
+    <signal name="Completed">
+      <arg name="success" type="b" direction="out"/>
+      <arg name="message" type="s" direction="out"/>
+    </signal>
+
+    <!-- For miscellaneous messages. -->
+    <signal name="Message">
+      <arg name="text" type="s" direction="out"/>
+    </signal>
+
     <signal name="DownloadProgress">
       <!-- time data, format is:
             start time, elapsed seconds

src/daemon/os.c

@@ -182,7 +182,8 @@ osstub_handle_download_update_rpm_diff (RPMOSTreeOS *interface,
 
 static gboolean
 osstub_handle_upgrade (RPMOSTreeOS *interface,
-                       GDBusMethodInvocation *invocation)
+                       GDBusMethodInvocation *invocation,
+                       GVariant *arg_options)
 {
   glnx_unref_object RPMOSTreeTransaction *transaction = NULL;
   glnx_unref_object GCancellable *cancellable = NULL;