Describe strasbourg network

Related to bug 13715.

This merge request describe more accurately Strasbourg's network.

Because the rate of fleckenstein's eth1 interface is not detected by g5k-checks, eth1 is currently not enabled on the cluster.

assigned to @pijacquo

added 6 commits

• ab152c7c...385241ef - 3 commits from branch master
• 63b14260 - [strasbour][gw] Describe port-channel of srv-data
• a2db0623 - [strasbourg][gw] Describe pve-1 & pve-2 as servers.
• eb4dbf1c - [strasbourg][network] Fix fleck's interfaces declaration

Compare with previous version

merged

mentioned in commit 318a9303