Align elasticsearch-env.sh.erb with elasticsearch.in.sh

[kimchy]

I suggest aligning elasticsearch-env.sh.erb with elasticsearch.in.sh that comes with elasticsearch installation. There is no need to use the max-open-files flag for example (its exposed in nodes info), AgressiveOpts is no longer recommended, and there are other flags in https://github.com/elasticsearch/elasticsearch/blob/master/bin/elasticsearch.in.sh that are recommended.

[karmi]

Yes, thanks for the nudge. I've copied over some configs from the Opscode cookbook. It would probably make sense to just use the provided file and somehow allow user to override it...