Add pry as a development dependancy.

Otherwise, our `rake console` doesn't work. :disapointed:
Add support for choosing instance based on layer.

Sometimes you just want to check the instance running cron. What happens
then? Huh? Adam happens!
Merge pull request #6 from freerunningtech/pry

Add pry as a development dependancy.
Merge pull request #8 from freerunningtech/layers

Add support for choosing instance based on layer.
Use simpler hash syntax.
Add unicorn command for restarting server.

Uses recipes!