Add Birch release box files to Vagrant files

vagrant/release/devstack/Vagrantfile

@@ -75,6 +75,9 @@ openedx_releases = {
   "named-release/birch.rc3" => {
     :name => "birch-devstack-rc3", :file => "20150213-birch-devstack-rc3.box",
   },
+  "named-release/birch" => {
+    :name => "birch-devstack", :file => "20150224-birch-devstack.box",
+  },
 }
 openedx_releases.default = {
   :name => "lavash-devstack", :file => "20141118-lavash-devstack.box"

vagrant/release/fullstack/Vagrantfile

@@ -27,6 +27,9 @@ openedx_releases = {
   "named-release/birch.rc3" => {
     :name => "birch-fullstack-rc3", :file => "20150213-birch-fullstack-rc3.box"
   },
+  "named-release/birch" => {
+    :name => "birch-fullstack", :file => "20150224-birch-fullstack.box",
+  },
 }
 openedx_releases.default = {
   :name => "kifli-fullstack", :file => "20140826-kifli-fullstack.box"