Added dev14 DevToolsVersion and powershell script

Author: ras0219-msft

Build/Common.Build.settings

@@ -38,6 +38,7 @@
     <TargetsPath>$(BuildRoot)\Build</TargetsPath>
     <OsVersion>$(registry:HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion@CurrentVersion)</OsVersion>
     <!--If Dev11 and Dev12 are both installed, the default is to build Dev12. This can be overridden by setting the DevToolsVersion variable in powershell-->
+	<DevToolsVersion Condition="'$(DevToolsVersion)' == '' And '$(VS140COMNTOOLS)' != ''">140</DevToolsVersion>
 	<DevToolsVersion Condition="'$(DevToolsVersion)' == '' And '$(VS120COMNTOOLS)' != ''">120</DevToolsVersion>
     <DevToolsVersion Condition="'$(DevToolsVersion)' == '' And '$(VS110COMNTOOLS)' != ''">110</DevToolsVersion>
     <!-- ARM tools are installed in $(FrameworkSdkDir)\DesignTime\CommonConfiguration\Neutral\Windows.desktop.arm.props -->

setup_ps_env_VS2014.ps1

@@ -0,0 +1,22 @@
+function Get-Batchfile ($file) {
+    $cmd = "@echo off & `"$file`" & set"
+    cmd /c $cmd | Foreach-Object {
+        $p, $v = $_.split('=')
+        Set-Item -path env:$p -value $v
+    }
+}
+
+function VsVars32()
+{
+    $vs140comntools = (Get-ChildItem env:VS140COMNTOOLS).Value
+    $batchFile = [System.IO.Path]::Combine($vs140comntools, "vsvars32.bat")
+    Get-Batchfile $BatchFile
+}
+
+"Initializing Casablanca Powershell VS2014 Environment"
+
+# get VS tools
+VsVars32
+
+$Env:VisualStudioVersion = "14.0"
+$Env:DevToolsVersion = "140"