OPENDJ-1628 - Simplify Index hierarchy and remove Indexer classes

Matthew Swift

07.45.2015 20fdcbef0d17440c367d2943f9c5799bddfe661f

opendj-server-legacy/src/main/java/org/opends/server/backends/pluggable/PresenceIndexer.java does not exist in tree 9b9926f393cd1e8a33fd1cc9bfd890bdc6daa02e