Verbose logs for missing consul keys

[crumley]

The logs for nginx-mantlui fill up with many of these WARN level messages. Perhaps a default should be provided if the keys are normally missing?

2016/07/20 16:21:46 [WARN] ("key(config/mantlui/ssl)") Consul returned no data (does the path exist?)
2016/07/20 16:21:48 [WARN] ("key(config/mantlui/ssl_ciphers)") Consul returned no data (does the path exist?)
2016/07/20 16:21:57 [WARN] ("key(config/mantl/auth)") Consul returned no data (does the path exist?)
2016/07/20 16:22:09 [WARN] ("key(config/mantl/consul_ssl)") Consul returned no data (does the path exist?)