Do not record log split time when handling separator

Previously handleSeparator() caused the ResearchLogger to mark the time at which a LogUnit should be
broken.  However, this causes the motion data associated with a separator to be associated with the
LogUnit of the previous word.  This change corrects this bug.

Change-Id: I8b4d4fa6de2a013de9e2a28bb668c446a07f1957