[SPARK-4688] Have a single shared network timeout in Spark

[SPARK-4688] Have a single shared network timeout in Spark
@Lewuathe , that is what I wanted to know. That what should I keep as the default value.  Keep a single fixed timeout value for the config spark.network.timeout or change the default based on defaults for earlier configurations which this config intends to replace. As I am pretty new to Spark, I am not aware of what default value will be suitable. Maybe @rxin can confirm.