Use cirros images.

Switched to using cirros images rather than ubuntu cloud images, as
they are smaller, and thus better for testing. They should also go
through the zuul reverse proxy.

Update env variables to work with the tweaks to snapstack.

Change-Id: I989f1d2eacefebd2a72f75897e09b2c8b9e856ef

tests/glance.sh

@@ -31,11 +31,14 @@ sudo systemctl restart snap.glance.*
 while ! nc -z localhost 9292; do sleep 0.1; done;
 
 openstack image show xenial || {
-    [ -f $HOME/images/xenial-server-cloudimg-amd64-disk1.img ] || {
+    [ -f $HOME/images/cirros-0.3.5-x86_64-disk.img ] || {
+        export http_proxy=$SNAPSTACK_HTTP_PROXY
         mkdir -p $HOME/images
-        wget http://cloud-images.ubuntu.com/xenial/current/xenial-server-cloudimg-amd64-disk1.img \
+        wget \
-            -O ${HOME}/images/xenial-server-cloudimg-amd64-disk1.img
+          http://download.cirros-cloud.net/0.3.5/cirros-0.3.5-x86_64-disk.img \
+          -O ${HOME}/images/cirros-0.3.5-x86_64-disk.img
+        unset http_proxy
     }
-    openstack image create --file ${HOME}/images/xenial-server-cloudimg-amd64-disk1.img \
+    openstack image create --file ${HOME}/images/cirros-0.3.5-x86_64-disk.img \
-        --public --container-format=bare --disk-format=qcow2 xenial
+        --public --container-format=bare --disk-format=qcow2 cirros
 }

tox.ini

@@ -8,7 +8,9 @@ install_command = pip install {opts} {packages}
 passenv =
     HOME
     TERM
-    SNAP_BUILD_PROXY
+    SNAPSTACK_HTTP_PROXY
+    SNAPSTACK_HTTPS_PROXY
+    
 whitelist_externals =
     sudo
     snapcraft