Bump all the versions

Bump:
- stern
- Ubuntu

Also, each place where there is a 'bumpable' version, I added
a ##VERSION## marker, easily greppable.

prepare-vms/lib/commands.sh

@@ -170,7 +170,8 @@ EOF"
     # Install stern
     pssh "
     if [ ! -x /usr/local/bin/stern ]; then
-        sudo curl -L -o /usr/local/bin/stern https://github.com/wercker/stern/releases/download/1.8.0/stern_linux_amd64 &&
+        ##VERSION##
+        sudo curl -L -o /usr/local/bin/stern https://github.com/wercker/stern/releases/download/1.10.0/stern_linux_amd64 &&
         sudo chmod +x /usr/local/bin/stern &&
         stern --completion bash | sudo tee /etc/bash_completion.d/stern
     fi"

prepare-vms/lib/infra/aws.sh

@@ -201,5 +201,6 @@ aws_tag_instances() {
 }
 
 aws_get_ami() {
-    find_ubuntu_ami -r $AWS_DEFAULT_REGION -a amd64 -v 16.04 -t hvm:ebs -N -q
+    ##VERSION##
+    find_ubuntu_ami -r $AWS_DEFAULT_REGION -a amd64 -v 18.04 -t hvm:ebs -N -q
 }

slides/k8s/logs-cli.md

@@ -62,10 +62,12 @@ Exactly what we need!
 - The following commands will install Stern on a Linux Intel 64 bit machine:
   ```bash
   sudo curl -L -o /usr/local/bin/stern \
-       https://github.com/wercker/stern/releases/download/1.8.0/stern_linux_amd64
+       https://github.com/wercker/stern/releases/download/1.10.0/stern_linux_amd64
   sudo chmod +x /usr/local/bin/stern
   ```
 
+<!-- ##VERSION## -->
+
 ---
 
 ## Using Stern

slides/k8s/setup-k8s.md

@@ -4,7 +4,9 @@
 
 --
 
-- We used `kubeadm` on freshly installed VM instances running Ubuntu 16.04 LTS
+<!-- ##VERSION## -->
+
+- We used `kubeadm` on freshly installed VM instances running Ubuntu 18.04 LTS
 
     1. Install Docker
 

slides/k8s/versions-k8s.md

@@ -1,9 +1,10 @@
 ## Versions installed
 
-- Kubernetes 1.12.0
-- Docker Engine 18.06.1-ce
+- Kubernetes 1.12.2
+- Docker Engine 18.09.0
 - Docker Compose 1.21.1
 
+<!-- ##VERSION## -->
 
 .exercise[