fix Elasticsearch 1.2.1 log path parsing

hello

I noticed I couldn't find the logs after installing Elasticsearch 1.2.1  This fixes the parsing in config.  Please review.  Thank you.

[1.2.1 config file (github)](https://github.com/elasticsearch/elasticsearch/blob/6c95b759f9e7ef0f8e17f77d850da43ce8a4b364/config/elasticsearch.yml#L155-L167)
Is this needed with a default config or only a modified one?