Adds 2 release network commands for Fuel CLI.

The following commands are introduced for Fuel CLI:

*   fuel rel --rel 1 --network --download (read rel-nets)
*   fuel rel --rel 1 --network --upload (upload back after modifying)

Change-Id: I11bf7b08f7cf4c71be5f6ccb1075b2c608081dc3
Closes-Bug: 1391207
Merge "Adds 2 release network commands for Fuel CLI."