[system-test]Deprecated option "--network" in test_cli.py

[Mikhail Samoylov]

Deprecated option "--network" in fuel env create mode. We must fix our tests, which use this option(for ex. test_cli.py).

1. Deploy master node with group prepare_release
2. Connect to master node as root
3. Execute command: "fuel env create --name 2 --rel 2 --network neutron --nst vlan"

actual result:
fuel env create --name 2 --rel 2 --network neutron --nst vlan
fuel: error: unrecognized arguments: --network neutron
expected result:
fuel env create --name 2 --rel 2 --nst vlan

release_versions:
  2015.1.0-8.0:
    VERSION:
      api: '1.0'
      astute_sha: 959b06c5ef8143125efd1727d350c050a922eb12
      build_id: '172'
      build_number: '172'
      feature_groups:
      - mirantis
      fuel-agent_sha: 61f741f4d89a3f1095dd8b494f82695fb69153d6
      fuel-createmirror_sha: 22a7aacd95bbdca69f9e0f08b70facabdec8fb28
      fuel-library_sha: 31aa9fb129a8b8739f8ca6ea186caa3c9f46820f
      fuel-nailgun-agent_sha: 3e9d17211d65c80bf97c8d83979979f6c7feb687
      fuel-nailgun_sha: f8ba3f9cd449363f1c08621307e7504c304c29ae
      fuel-ostf_sha: 9690a2de829d3b063ed1e64b0b10dde39f711dc0
      fuel-upgrade_sha: 1e894e26d4e1423a9b0d66abd6a79505f4175ff6
      fuelmain_sha: 266f9b374934c64629a84b5146632cc0de70ac91
      fuelmenu_sha: 06bbcebed6c8d0b0f9279e2997d2f958c800e98c
      network-checker_sha: a57e1d69acb5e765eb22cab0251c589cd76f51da
      openstack_version: 2015.1.0-8.0
      production: docker
      python-fuelclient_sha: e685d68c1c0d0fa0491a250f07d9c3a8d0f9608c
      release: '8.0'
      shotgun_sha: c377d163519f6d10b69a654019d6086ba5f14edc
shotgun_sha: c377d163519f6d10b69a654019d6086ba5f14edc