Fix the way JavaHL's remote API retreives dated revisions.

[in subversion/bindings/javahl/src/org/apache/subversion/javahl]
* ISVNRemote.java (ISVNRemote.getRevisionByTimestamp): Fix docstrung.
   The timestamp must be in microseconds, not milliseconds.
* remote/RemoteSession.java (RemoteSession.getRevisionByDate):
   Fix conversion from Date when calling getRevisionByTimestamp to
   return microseconds, not nanoseconds.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1577176 13f79535-47bb-0310-9956-ffa450edef68