modified:   MapReduce_2_1_ReduceTask.md
	renamed:    MapReduce_2_2_CopyPhase.md -> MapReduce_2_2_CopyPhase_and_SortPahse.md
	renamed:    MapReduce_2_4_Reducer.md -> MapReduce_2_3_Reducer.md
	deleted:    MapReduce_2_3_SortPhase.md