Setup local development environment easily

Until now, it is so difficult to setup prepan development environment.  So I fix script/setup.sh to build local environment automatically.

script/setup.sh execute followings,
- Install Carton to manage moudle dependency, if carton doesn't exist
- Install perl module dependency by carton
- setup db for local development and test
- copy development config: local/development.eg.pl -> local/development.pl

Also I wrote about how to build local environment and setup Twitter OAuth config.