[MINDEXER-118] Eliminate use of deprecated Lucene API - Field

Refactor to avoid using the following deprecated symbols:
 * Field.Index
 * Field.TermVector
 * Token

These symbols only exist to support transitioning from pre-4.0
Lucene APIs, so this will make it easier to move to newer Lucenes
in the future.

Signed-off-by: Mat Booth <mat.booth@redhat.com>
13 files changed