Issue #54: Getting started with cfn-init

Issue #54: Getting started with cfn-init

Implemented features:
  * sysv and systemd service handling
  * yum package management

Running the script:
  e.g., sudo python cfn-init -f resource-metadata.json

Example resource metadata file contents:
{
    "AWS::CloudFormation::Init": {
        "config": {
            "packages": {
                "yum": {
                    "rubygem-fattr" : []
                }
            },
            "services": {
                "sysvinit": {
                    "httpd": {
                        "enabled" : "true",
                        "ensureRunning" : "true"
                    }
                }
            }
        }
    }
}