Adds ability to specify the aws credentials as environment variables
Adds ability to specify the aws credentials as environment variables

Original commit: elastic/x-pack-elasticsearch@c22428069e46bcf3610324f90670c9ad61aa19c9

strapdata/elassandra,GlenRSmith/elasticsearch,nknize/elasticsearch,GlenRSmith/elasticsearch,uschindler/elasticsearch,strapdata/elassandra,nknize/elasticsearch,coding0011/elasticsearch,strapdata/elassandra,gingerwizard/elasticsearch,gingerwizard/elasticsearch,gfyoung/elasticsearch,HonzaKral/elasticsearch,strapdata/elassandra,HonzaKral/elasticsearch,robin13/elasticsearch,scorpionvicky/elasticsearch,HonzaKral/elasticsearch,robin13/elasticsearch,scorpionvicky/elasticsearch,gingerwizard/elasticsearch,scorpionvicky/elasticsearch,robin13/elasticsearch,nknize/elasticsearch,vroyer/elassandra,uschindler/elasticsearch,coding0011/elasticsearch,coding0011/elasticsearch,uschindler/elasticsearch,coding0011/elasticsearch,scorpionvicky/elasticsearch,scorpionvicky/elasticsearch,nknize/elasticsearch,GlenRSmith/elasticsearch,GlenRSmith/elasticsearch,strapdata/elassandra,robin13/elasticsearch,gingerwizard/elasticsearch,gfyoung/elasticsearch,robin13/elasticsearch,uschindler/elasticsearch,gfyoung/elasticsearch,gingerwizard/elasticsearch,coding0011/elasticsearch,gfyoung/elasticsearch,gfyoung/elasticsearch,vroyer/elassandra,GlenRSmith/elasticsearch,uschindler/elasticsearch,HonzaKral/elasticsearch,vroyer/elassandra,nknize/elasticsearch,gingerwizard/elasticsearch,gingerwizard/elasticsearch