Node builder API

We've had the need several times for a simple node building api - especially in version handlers - to construct relatively simple nodes (couple of nodes, couple of properties) without having to maintain complex bootstrap or properties file, and verbose/long code. I'd like to propose a simple DSL/API similar to the one used to build tasks and deltas for this.

Additional notes:

• this should be useable in the context of "for each" tasks
• debuggability/self-descriptiveness
  Readability (structure of code ~= structure of nodes)
  Readability (names and intentions are clear)
  Writability (must be error-safe)
  Conciseness
  ide-friendly (indentation)
  Useable in the context of "for each" kind of update tasks
  Debuggability (i.e self-descriptive, code should be followable with a debugger, or we should be able to generate/dump a description, ...)