airbnb/synapse — pull request #55 by ryotarai (2014-03-27 14:13:57+00:00)
Title: Fix a bug raising an error without shared_frontend.

shared_frontend is optional config.

Without this patch, NoMethodError will be raised:
```
/vagrant/lib/synapse/haproxy.rb:560:in `generate_config': undefined method `flatten' for nil:NilClass (NoMethodError)
```