ACCUMULO-1998 Defense against concurrent write() and close() by relying on DfsLogger output stream interaction
ACCUMULO-2173 use suffixes when comparing paths
documentation update regarding placement of WAL files (to reflect 1.5+ functionality)

Signed-off-by: Josh Elser <elserj@apache.org>
Merge branch '1.5.1-SNAPSHOT' into 1.6.0-SNAPSHOT
Merge branch '1.6.0-SNAPSHOT'