RottenPotatoes Live Demo Scripts

* Chp 4 and 5 involve adding a lot to the RP app  - it can be challenging to figure out the live demo setup. 
* Creating a script for each of the `rails` subcommands is not too hard.
* Is there an easy way for us to keep N versions of RP such that you can check out a version in a useful state before a lecture?
* Would be good to have a nicer seeds script with a dozen movies or so.