Expose the microsecond timestamp in JavaHL's info class, to match the Status class.

* subversion/bindings/javahl/src/org/apache/subversion/javahl/types/Info.java
  (Info.getLastChangedDateMicros): New method.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1577179 13f79535-47bb-0310-9956-ffa450edef68