ACCUMULO-2974 Include the table id when constructing an absolute path from a relative.

Testing that the TabletGroupWatcher does the correct path is difficult, and also doesn't
prevent other callers from writing the same bug, so the fix is added to VolumeManagerImpl
with appropriate tests added to ensure failure happens.
Merge branch '1.6.1-SNAPSHOT'
ACCUMULO-2974 Hadoop's StringUtils changes across 1 and 2, so switch it to commons-lang
Merge branch '1.6.1-SNAPSHOT'