Make label scan store available in consistency checker.

o Make neo4j-consistency-check depend on neo4j-lucene-index
o Add LuceneLabelScanStoreBuilder as a second, straightforward way to instantiate LuceneLabelScanStore that bypasses kernel extensions
 (which are difficult to instantiate freestanding without starting a full database)
Merge pull request #1374 from boggle/2.0-label-scan-store-verification

Make label scan store available in consistency checker.