Default_to_MODIN_CPU #57
Description
Create the same functionality as default_to_pandas, but for modin-cpu. Basically, send the partitions to the CPU.
Basic functionality: Given an operation that is not attainable in cudf, transfer the partitions to the CPU and perform the operation in a distributed fashion.
Extended functionality: Keep a "dirty" flag to know whether or not we need to update the GPU cache after the operation is done and we are deciding whether or not to send back the CPU partition to GPU.