TaskInfo in history parser should not depend on the apache directory project

Uses
import org.apache.directory.api.util.Strings;

We should not be depending on this - especially for a Strings utility class.
We also don't have an explicit dependency, assuming this comes in as a result of hadoop being pulled in.

Appears to be in 0.8.0 only. (The class exists in api-util-1.0.0-M20.jar - pulled in by hadoop-auth)