Better Docker Integration

This is a follow-up of JBDS-3317 and JBDS-3258 to collect all the remaining features that were not implemented:

• API for server tooling
• Support for build options (https://bugs.eclipse.org/bugs/show_bug.cgi?id=474196)
• Support for .dockerignore file (https://bugs.eclipse.org/bugs/show_bug.cgi?id=469819))
• Show ports, environment variables and links in the UI (https://bugs.eclipse.org/bugs/show_bug.cgi?id=471666)