Bump to 0.5-SNAPSHOT for future work.
Reindent S3Helpers and use better package syntax.
Move S3Helpers to AWS Java SDK.

Jets3t was fun and all, but we’re about to need to support IAM
roles, and the AWS Java SDK does this with minimal work. Git
rdy!
Support IAM roles in S3 deployment.

We do this by making the specification of access keys and
secret keys optional, and creating an S3 client without
credentials if they are absent.
Fix withAwsConfiguration invocation parameter ordering.
Add content length to object metadata in S3Helpers.

This suppresses an AWS warning about reading a whole
stream into memory, which isn’t a huge concern, but gets a bit
noisy.
Add a blurb to the README concerning IAM roles.
Merge pull request #28 from Shadowfiend/iam-iron-man

Switch to AWS's Java SDK to properly support IAM role auth. Make the AWS secret and access key truly optional because IAM roles don't require these to be set, and the SDK does all the work when they aren't. Bumps the version to 0.5-SNAPSHOT.