LUCENE-5339: add abstract Facets base class; fix separate test failure

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene5339@1542062 13f79535-47bb-0310-9956-ffa450edef68
eclipse rename

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene5339@1542065 13f79535-47bb-0310-9956-ffa450edef68