Pinning a few dependencies versions.

.gitignore

@@ -222,5 +222,6 @@ AppPackages
 project.lock.json
 msbuild.binlog
 *.project.lock.json
-/build/tools
+/build/tools/**
+!/build/tools/packages.config
 /build/dotnet-install.ps1

build/build.cake

@@ -1,7 +1,7 @@
 #module nuget:?package=Cake.LongPath.Module&version=0.5.0
 
-#addin "Cake.FileHelpers"
-#addin "Cake.Powershell"
+#addin nuget:?package=Cake.FileHelpers&version=3.2.1
+#addin nuget:?package=Cake.Powershell&version=0.4.8
 
 using System;
 using System.Linq;

build/tools/packages.config

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<packages>
+    <package id="Cake" version="0.35.0" />
+</packages>