Removed some shuffle implementations. Remaining ones all use local files

core/src/main/scala/spark/CustomBlockedInMemoryShuffle.scala

core/src/main/scala/spark/CustomParallelFakeShuffle.scala

.../src/main/scala/spark/CustomParallelInMemoryShuffle.scala

core/src/main/scala/spark/HttpBlockedLocalFileShuffle.scala

.../src/main/scala/spark/ManualBlockedLocalFileShuffle.scala

core/src/main/scala/spark/ShuffleTrackerStrategy.scala

...ain/scala/spark/TrackedCustomBlockedInMemoryShuffle.scala

...in/scala/spark/TrackedCustomBlockedLocalFileShuffle.scala

...n/scala/spark/TrackedCustomParallelLocalFileShuffle.scala