User Guide: Fix auth script

Fix script,  we need to use env.get to allow not-set environment value.

Change-Id: I61a36bfc2b5fbf412edbbdef973bb09880aa9967
Closes-Bug: #1315763
Correct second network to be labeled as such

Change-Id: I9cbce119cfd1604c6f63543e4037433d27c48c88
Closes-bug: 1316408
corrected intents of screen environments

Also merged several screen environments in the Hyper-V chapter.

Change-Id: Ib81eafbf1429c881260958548676b884b4a15cca
Merge "Correct second network to be labeled as such"
Merge "User Guide: Fix auth script"