Bug 518448: [Tooling] Decide whether UML-RT architecture context shall be default context in Papyrus-RT 1.0 or not

Add UML-RT architecture context to the end-user setup.

https://bugs.eclipse.org/bugs/show_bug.cgi?id=518448
diff --git a/content/setup/papyrus-rt.setup b/content/setup/papyrus-rt.setup
index afaf6d0..bd5ffda 100644
--- a/content/setup/papyrus-rt.setup
+++ b/content/setup/papyrus-rt.setup
@@ -83,10 +83,13 @@
   </setupTask>
   <setupTask
       xsi:type="setup:PreferenceTask"
+      key="/instance/org.eclipse.papyrus.infra.architecture/defaultContext"
+      value="org.eclipse.papyrusrt.umlrt.architecture"/>
+  <!-- Delete these for Oxygen release (but they would be harmless). -->
+  <setupTask
+      xsi:type="setup:PreferenceTask"
       key="/instance/org.eclipse.papyrus.infra.viewpoints.policy/papyrusViewpointsConfigurationType"
-      value="extension">
-    <description></description>
-  </setupTask>
+      value="extension"/>
   <setupTask
       xsi:type="setup:PreferenceTask"
       key="/instance/org.eclipse.papyrus.infra.viewpoints.policy/papyrusViewpointsSelectedViewpoint"
@@ -95,6 +98,7 @@
       xsi:type="setup:PreferenceTask"
       key="/instance/org.eclipse.papyrus.infra.viewpoints.policy/papyrusViewpointsSelectedStakeholder"
       value="UML-RT Modeler"/>
+  <!-- End delete-me -->
   <setupTask
       xsi:type="setup:PreferenceTask"
       key="/instance/org.eclipse.egit.ui/enable_logical_model"