Move CSV-specific classes into CSV-renderer

Don't expose outside the CSV rendering class all the details
about the event-specific field rendering.

This is a preparation work to rename "rendering" to "formatting"
and thus simply the configuration to:

[plugin "audit-sl4j"]
  format = JSON

Change-Id: Ib30791102f0f2ec5db31890d713c15d22d42e0f7
7 files changed
tree: 73ab401d3b0148a9520f86ea817e2a500e1cd74b
  1. src/
  2. .gitignore
  3. BUILD