Revert "Upgrade to Debian 9 (a.k.a. stretch)"

Oops. I accidentally pushed to master...

This reverts commit 29443be0516152967061adb3eda60774daf4d380.

Change-Id: I853bf174dfff592ff6de0928adc88037f7e4a269
diff --git a/vm/Vagrantfile b/vm/Vagrantfile
index e72e26a..1404131 100644
--- a/vm/Vagrantfile
+++ b/vm/Vagrantfile
@@ -16,12 +16,12 @@
   # please see the online documentation at vagrantup.com.
 
   # Every Vagrant virtual environment requires a box to build off of.
-  config.vm.box = "debian/stretch64"
+  config.vm.box = "debian/jessie64"
 
   config.vm.provider "virtualbox" do |vb|
     # Don't boot with headless mode
     vb.gui = true
-    vb.name = "FRC971-Development-2018"
+    vb.name = "FRC971-Development-2017"
 
     # There are two shortcuts for modifying number of CPUs and amount of
     # memory. Modify them to your liking.