Unit 6: Miscellaneous

- 06-01: PostgreSQL setup scripts
- 06-02: Tree commands
- 06-03: Annotate
- 06-04: rails-erd
- 06-05: railroady
- 06-06: Gem dependency diagram
- 06-07: Mailcatcher
- 06-08: Better Errors
- 06-09: Binding of Caller
- 06-10: pry-rails
- 06-11: Gem Upgrade Script