Customized S2I builder

[thoraxe]

One of the things I always wanted to do with S2I was to show our automated build triggering on changes to the S2I image.

Other ideas:

1. Company requires all images produced to contain some form of organizational identifier (such as a version.txt file
2. Fine-grained customization of the JBoss EAP standalone.xml file (support for the Vault, fine-grained customization of electron [security])
3. Gradle instead of Maven
4. Customization of the build (assemble) or run script.