## What changes were proposed in this pull request?
As the title says, this moves the three modules currently in network/ into common/network-*. This removes one top level, non-user-facing folder.
## How was this patch tested?
Compilation and existing tests. We should run both SBT and Maven.
Author: Reynold Xin <rxin@databricks.com>
Closes#11409 from rxin/SPARK-13529.