Add dogwood rc1 box to release Vagrantfiles

vagrant/release/devstack/Vagrantfile

@@ -60,6 +60,12 @@ end
 # to a name and a file path, which are used for retrieving
 # a Vagrant box from the internet.
 openedx_releases = {
+  "named-release/dogwood.rc" => {
+    :name => "dogwood-devstack-rc2", :file => "20151221-dogwood-devstack-rc2.box",
+  },
+  "named-release/dogwood.rc2" => {
+    :name => "dogwood-devstack-rc2", :file => "20151221-dogwood-devstack-rc2.box",
+  },
   "named-release/cypress" => {
     :name => "cypress-devstack", :file => "cypress-devstack.box",
   },

vagrant/release/fullstack/Vagrantfile

@@ -9,6 +9,12 @@ CPU_COUNT = 2
 # to a name and a file path, which are used for retrieving
 # a Vagrant box from the internet.
 openedx_releases = {
+  "named-release/dogwood.rc" => {
+    :name => "dogwood-fullstack-rc2", :file => "20151221-dogwood-fullstack-rc2.box",
+  },
+  "named-release/dogwood.rc2" => {
+    :name => "dogwood-fullstack-rc2", :file => "20151221-dogwood-fullstack-rc2.box",
+  },
   "named-release/cypress" => {
     :name => "cypress-fullstack", :file => "cypress-fullstack.box",
   },