following http://confluence.atlassian.com/display/BAMBOO/Creating+a+Custom+Elastic+Image
assumes the following artifacts to be in webapp/atlassian-bamboo-agent-elastic-assembly-2.4.0.tar.gz
- bamboo-capabilities.properties in components/bamboo-agent-elastic-image-default/src/main/ec2
- rc.local in components/bamboo-agent-elastic-image-default/src/main/ec2