Provide pluggable APIs to support user customized compression codec

[Dong, Xin]

Hi,
In demand of better performance, quite some end users want to leverage 
accelerators (e.g. FPGA, Intel QAT) to offload compression computation. 
However, in current parquet-mr code, codec implementation can't be customized 
to leverage accelerators. We would like to proposal a pluggable API to support 
the customized compression codec.
I've opened a JIRA https://issues.apache.org/jira/browse/PARQUET-1804 for this 
issue. What's your throughts on this issue?
Best Regards,
Xin Dong