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/cli/main_test.rb

@@ -95,7 +95,7 @@ class CliMainTest < CliTestCase
     run_command("rollback", "123").tap do |output|
       assert_match "Start version 123", output
       assert_match "docker start app-123", output
-      assert_match "docker container ls --all --filter name=app-version-to-rollback --quiet | xargs docker stop", output, "Should stop the container that was previously running"
+      assert_match "docker container ls --all --filter name=^app-version-to-rollback$ --quiet | xargs docker stop", output, "Should stop the container that was previously running"
     end
   end