Support CodeCommit repo integration

[patrickbrandt]

Currently, username and password creds are used to interface with github repos. We'll need to support automated integration to code-commit, either via ssh or relying on instance IAM role.

[clearly]

The ec2 instance should use an IAM profile that allows any actions that any tasks in the pipeline need as well as access to CodeCommit. Also add the following file

/etc/gitconfig

[credential]
        helper = !aws codecommit credential-helper $@
        UseHttpPath = true