Enable network creation

[MarcHarriss]

gscloud network --help

List, create, or remove networks.

Usage:
  gscloud network [command]

Available Commands:
  ls          List networks
  rm          Remove network

Global Flags:
      --account string   Specify the account used (default "default")
      --config string    Specify a configuration file (default "/Users/mharriss/Library/Application Support/gscloud/config.yaml")
  -h, --help             Print usage
  -j, --json             Print JSON to stdout instead of a table
      --noheading        Do not print column headings
  -q, --quiet            Print only IDs of objects

Use "gscloud network [command] --help" for more information about a command.

but it doens't seem that the "create" command has been implemented yet

so this task is to implement + add documentation