Don't build tools for which the script won't prepare the system.

Our current simple instructions do not include any mention of, nor does the current devlibs.zip contain, Qt5 (required for building Tools) or PyGTK (required to build resource.dat).  This removes those projects by default for people using this script.

prepare_env.ps1

@@ -27,7 +27,7 @@ if (!(Test-Path -PathType Container devlibs)) {
 }
 
 Write-Host "Running CMake to configure build system... "
-cmake -DCMAKE_INSTALL_PREFIX=devlibs -G "Visual Studio 12" ..
+cmake -DCMAKE_INSTALL_PREFIX=devlibs -DPLASMA_BUILD_TOOLS=OFF -DPLASMA_BUILD_RESOURCE_DAT=OFF -G "Visual Studio 12" ..
 
 if ($Host.Name -eq "ConsoleHost") {
     Write-Host ""