[#75] Fixed incorrect configuration for `discovery.ec2.group`
[#75] Fixed incorrect configuration for `discovery.ec2.group`

Fixing issue with AWS plugin, attribute for security group should be discovery.ec2.group

gilt/cookbook-elasticsearch,vacay/vcy-elasticsearch,gouketsu/cookbook-elasticsearch,gouketsu/cookbook-elasticsearch,gouketsu/cookbook-elasticsearch,nbudin/cookbook-elasticsearch,paulczar/cookbook-elasticsearch,bavardage/cookbook-elasticsearch,zzugg/cookbook-elasticsearch,vacay/vcy-elasticsearch,GemHQ/cookbook-elasticsearch,nbudin/cookbook-elasticsearch,zzugg/cookbook-elasticsearch,spuder/cookbook-elasticsearch,zzugg/cookbook-elasticsearch,nbudin/cookbook-elasticsearch,gilt/cookbook-elasticsearch,michaeld/elasticsearch-cookbook,gilt/cookbook-elasticsearch,spuder/cookbook-elasticsearch,vacay/vcy-elasticsearch,spuder/cookbook-elasticsearch