Another Spark jobserver project

[melin]

Before doing big data platform products based on spark, the jobserver service is needed, and the design of many spark-jobservers is referred to. Now this part is also detached and processed as open source:
https://github.com/melin/spark-jobserver

[emmanuel-h]

@melin Sadly your jobserver is unusable for most people, as the documentation is not English-written.