Zero downtime redeploys

When deploying check if there is already a container with the existing
name. If there is rename it to "<version>_<random_hex_string>" to remove
the name clash with the new container we want to boot.

We can then do the normal zero downtime run/wait/stop.

While implementing this I discovered the --filter name=foo does a
substring match for foo, so I've updated those filters to do an exact
match instead.

test/commands/traefik_test.rb

@@ -82,7 +82,7 @@ class CommandsTraefikTest < ActiveSupport::TestCase
 
   test "traefik info" do
     assert_equal \
-      "docker ps --filter name=traefik",
+      "docker ps --filter name=^traefik$",
       new_command.info.join(" ")
   end