Catch, backoff and retry when receiving cloud formation rate exceeded error

this is a fairly common occurance and can provide for a improved user experience if inside the application.

/usr/local/rvm/gems/ruby-2.0.0-p353@sts/gems/simple_deploy-0.8.0/lib/simple_deploy/aws/cloud_formation/error.rb:22:in `process': Throttling => Rate exceeded (SimpleDeploy::Exceptions::CloudFormationError)
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/gems/simple_deploy-0.8.0/lib/simple_deploy/aws/cloud_formation.rb:45:in`rescue in describe_stack'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/gems/simple_deploy-0.8.0/lib/simple_deploy/aws/cloud_formation.rb:43:in `describe_stack'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/gems/simple_deploy-0.8.0/lib/simple_deploy/aws/cloud_formation.rb:61:in`stack_status'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/gems/simple_deploy-0.8.0/lib/simple_deploy/stack/stack_reader.rb:18:in `status'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/gems/simple_deploy-0.8.0/lib/simple_deploy/stack/status.rb:46:in`current'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/gems/simple_deploy-0.8.0/lib/simple_deploy/stack/status.rb:27:in `create_failed?'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/gems/simple_deploy-0.8.0/lib/simple_deploy/stack/status.rb:31:in`stable?'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/gems/simple_deploy-0.8.0/lib/simple_deploy/stack/status.rb:40:in `wait_for_stable'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/gems/simple_deploy-0.8.0/lib/simple_deploy/stack/stack_updater.rb:27:in`update'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/gems/simple_deploy-0.8.0/lib/simple_deploy/stack/stack_updater.rb:17:in `update_stack'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/gems/simple_deploy-0.8.0/lib/simple_deploy/stack.rb:54:in`update'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/gems/simple_deploy-0.8.0/lib/simple_deploy/stack/deployment/status.rb:39:in `set_deployment_in_progress'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/gems/simple_deploy-0.8.0/lib/simple_deploy/stack/deployment.rb:28:in`execute'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/gems/simple_deploy-0.8.0/lib/simple_deploy/stack.rb:83:in `deploy'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/gems/simple_deploy-0.8.0/lib/simple_deploy/cli/deploy.rb:87:in`block in deploy'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/gems/simple_deploy-0.8.0/lib/simple_deploy/cli/deploy.rb:64:in `each'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/gems/simple_deploy-0.8.0/lib/simple_deploy/cli/deploy.rb:64:in`deploy'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/gems/simple_deploy-0.8.0/lib/simple_deploy/cli.rb:39:in `start'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/gems/simple_deploy-0.8.0/bin/simple_deploy:6:in`'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/bin/simple_deploy:19:in `load'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/bin/simple_deploy:19:in`'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/bin/ruby_executable_hooks:15:in `eval'
from /usr/local/rvm/gems/ruby-2.0.0-p353@sts/bin/ruby_executable_hooks:15:in`'