update to: ruby-2.0.0-p247

Also:

- Gemfile updates:
  rake, librarian, shutterbug, guard-sass. guard-livereload,
  thor, capistrano, rvm-capistrano

- Gemfile new gems:
  rack-livereload

- Gemfile removed gems:
  rack-rewrite

- new :environment variable in config.yml

:environment can be 'development' or 'production'

production:
 - delivers minimized javascript resources
 - sets JavaScript variable: Lab.config.environment = 'production'

development:
 - delivers un-minimized javascript resources
 - sets JavaScript variable: Lab.config.environment = 'development'
 - enables rack-livereload (no-longer need to install extension in browser)

Fixed Guardfile for watching top-level markdown files.
Gemfile updates: librarian-chef
simplify setup:server cap task