Specs for app maintenance

Added ability for custom formatters
explicit require of paratrooper/deploy
DRY up formatter through specs
Adding pry as a development dependency
Specs for Deploy#update_repo_tag

moved system calls into SystemCaller for testing ease
Specs for Deploy#push_repo
Specs for Deploy#run_migrations
Specs for Deploy#app_restart
Specs for Deploy#warm_instance
Merge pull request #1 from mattpolito/specs

Specs for Paratrooper::Deploy