FileSystem: Use XNativeFSLockFactory instead of the buggy Lucene 4.8.1 v...

...ersion

There is a pretty nasty bug in the lock factory we use that can cause
nodes to use the same data dir wiping each others data. Luckily this is
unlikely to happen if the nodes are running in different JVM which they
do unless they are embedded.

See LUCENE-5738

Closes #6424