Update base image to Ruby 2.6.2 based image

Update base image to Ruby 2.6.2 based image

Following extensive internal testing it is time to update our common base image to 2.6.2 based one.

This also update various libraries, nginx and so on.

diff --git a/launcher b/launcher
index d2ff6ad..4e61592 100755
--- a/launcher
+++ b/launcher
@@ -81,7 +81,7 @@ git_rec_version='1.8.0'
 config_file=containers/"$config".yml
 cidbootstrap=cids/"$config"_bootstrap.cid
 local_discourse=local_discourse
-image=discourse/base:2.0.20190217
+image="discourse/base:2.0.20190321-0122"
 docker_path=`which docker.io 2> /dev/null || which docker`
 git_path=`which git`

GitHub sha: 2f7a204e