Add --host bind flag + gitignore tools/ (Docker demo scaffolding)

- server --host (default 127.0.0.1) so it can bind 0.0.0.0 inside a
  container
- gitignore tools/ (untracked local Docker/export scripts)

.gitignore

@@ -8,3 +8,4 @@ build/
 decode-errors.log
 auth-test.log
 .DS_Store
+tools/