JERSEY-1776: Updated to JAX-RS 2.0-rc2 API.

- Updated Link, Link.Builder implantation to reflect new API changes.
- Updated ClientBuilder, Client, WebTarget, Invocation, Invocation.Builder to reflect new API changes.
- Renamed replaceWith(Configuration) to loadFrom(Configuration).
- Removed preInitialize() support from Invocation and Invocation.Builder.
- Updated existing tests to reflect API changes (no new tests to cover new functionality added yet).

Change-Id: I91dfb46b9a628299e2f1926827ff5494ffaf1f15
Signed-off-by: Marek Potociar <marek.potociar@oracle.com>