s3_object_key_format accepts hostname, uuid, etc. parameters from fluent-mixin-config-placeholders
use the %{} placeholder from fluent-mixin-config-placeholders & brush up the readme
Merge pull request #19 from ijin/master

support for hostname, uuid, etc. from fluent-mixin-config-placeholders
use a newer version of aws-sdk to refresh expired credentials for IAM roles
create S3 bucket if not exists
fix missing parameter
Merge pull request #22 from naoya/proposal/create_bucket

create S3 bucket if not exists
Bucket existence and apikeys check moved to start method
Fix test
Add auto_create_bucket related tests
update to use aws-sdk v1.8.2
Merge pull request #21 from ijin/master

update aws-sdk version to refresh expiring IAM credentials
v0.3.0
Removed 'required' from some parameters in README

aws_key_id and aws_sec_key is not required if the agent is running on EC2 instance with an IAM Instance Profile.
Merge pull request #23 from rch850/patch-1

Removed 'required' from some parameters in README