Documentation tweaks.

- Added configurable Jersey & JAX-RS version support.
- Refactored JAX-RS link entities.
- Added new entity definitions for Jersey links (apidocs, user guide).
- Updated Jersey User Guide preface with typesetting/font conventions.

Change-Id: I58230dc6f1f1ea5cecbaef41684f9550120ea966
Signed-off-by: Marek Potociar <marek.potociar@oracle.com>