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_wsl.ps1

@@ -0,0 +1,40 @@
+# Description: Boxstarter Script
+# Author: Microsoft
+# Common dev settings for machine learning using Windows and Linux native tools
+
+Disable-UAC
+
+# Get the base URI path from the ScriptToCall value
+$bstrappackage = "-bootstrapPackage"
+$Boxstarter | Foreach-Object { write-host "The key name is $_.Key and value is $_.Value"  }
+
+$helperUri = $Boxstarter['ScriptToCall']
+write-host "ScriptToCall is $helperUri"
+
+$strpos = $helperUri.IndexOf($bstrappackage)
+$helperUri = $helperUri.Substring($strpos + $bstrappackage.Length)
+$helperUri = $helperUri.TrimStart("'", " ")
+$helperUri = $helperUri.TrimEnd("'", " ")
+$helperUri = $helperUri.Substring(0, $helperUri.LastIndexOf("/"))
+$helperUri += "/scripts"
+write-host "helper script base URI is $helperUri"
+
+function executeScript {
+    Param ([string]$script)
+    write-host "executing $helperUri/$script ..."
+	iex ((new-object net.webclient).DownloadString("$helperUri/$script"))
+}
+
+#--- Setting up Windows ---
+executeScript "SystemConfiguration.ps1";
+executeScript "FileExplorerSettings.ps1";
+executeScript "RemoveDefaultApps.ps1";
+executeScript "CommonDevTools.ps1";
+executeScript "VirtualizationTools.ps1";
+executeScript "GetMLPythonSamplesOffGithub.ps1";
+
+# TODO: now install additional ML tools inside the WSL distro once default user w/blank password is working
+
+Enable-UAC
+Enable-MicrosoftUpdate
+Install-WindowsUpdate -acceptEula