Install Ubuntu 18 and improve ML recipe setup (#66)

* move to Ubuntu 18 
* created two ML recipes
* using update-sessionenvironmnet instead of refreshenv
* discover helper script URI rather than hardcode it
* fixing readme links to support reboot

dev_ml_windows.ps1

@@ -0,0 +1,28 @@
+# Description: Boxstarter Script
+# Author: Microsoft
+# Common dev settings for machine learning using only Windows native tools
+
+Disable-UAC
+
+# see if we can't get calling URL somehow, that would eliminate this need
+# should move to a config file
+$user = "Microsoft";
+$baseBranch = "MLSamples";
+$finalBaseHelperUri = "https://raw.githubusercontent.com/$user/windows-dev-box-setup-scripts/$baseBranch/scripts";
+
+function executeScript {
+    Param ([string]$script)
+    write-host "executing $finalBaseHelperUri/$script ..."
+	iex ((new-object net.webclient).DownloadString("$finalBaseHelperUri/$script"))
+}
+
+#--- Setting up Windows ---
+executeScript "SystemConfiguration.ps1";
+executeScript "FileExplorerSettings.ps1";
+executeScript "RemoveDefaultApps.ps1";
+executeScript "GetMLIDEAndTooling.ps1";
+executeScript "PythonMLTools.ps1";
+
+Enable-UAC
+Enable-MicrosoftUpdate
+Install-WindowsUpdate -acceptEula