OPENDJ-2016: New on disk merge import strategy based on storage engine.

Yannick Lecaillez

09.07.2015 641e89ef0e15c9edde69f3b8cf82c7dd5f68687a

opendj-server-legacy/src/main/java/org/opends/server/backends/pluggable/IndexInputBuffer.java does not exist in tree 014a3ced3671406f1de5ed7a420d819ba36e9db5