tools: enable install-debian to work with VSTS Hosted Linux Preview (#5659)

Added -skip-sudo-check, because the check fails in VSTS Hosted Linux Preview even though sudo works.

tools/installpsh-debian.sh

@@ -14,10 +14,10 @@
 #Switches
 #  -includeide - the script is being run headless, do not perform actions that require response from the console
 #  -interactivetests - requires a human user in front of the machine - loads a script into the ide to test with F5 to ensure the IDE can run scripts
+#  -skip-sudo-check - skips the check that the user has permission to use sudo.  This is required to run in the VSTS Hosted Linux Preview.
 
 #gitrepo paths are overrideable to run from your own fork or branch for testing or private distribution
 
-
 VERSION="1.1.2"
 gitreposubpath="PowerShell/PowerShell/master"
 gitreposcriptroot="https://raw.githubusercontent.com/$gitreposubpath/tools"
@@ -94,7 +94,7 @@ if (( $EUID != 0 )); then
 fi
 
 #Check that sudo is available
-if [[ "$SUDO" -eq "sudo" ]]; then
+if [[ "$SUDO" -eq "sudo" && ! ("'$*'" =~ skip-sudo-check) ]]; then
 
     $SUDO -v
     if [ $? -ne 0 ]; then