Add cli commands to work with release networks

Added two commands to read/modify release networks

fuel rel --rel 1 --networks --download
Read networks from api and saves them in yaml format
on file system, you should be able to modify them and
send back with

fuel rel --rel 1 --networks --upload

DocImpact
Change-Id: I774ab8341b45a86bbf77d266aa788424936776cc
Merge "Add cli commands to work with release networks"