(chocolateyGH-90) Implemented Caching Package list to File

The Get-ChocoInstalledPackage function pulls a new list from
'choco list -lo -r' costing measurable system impact when choco is
installing several packages.

This commit will allow the Installed package list to be cached locally
in the $env:ChocolateyInstall folder for 60 seconds before pulling a
new list.

# Conflicts:
#	DSCResources/cChocoPackageInstall/cChocoPackageInstall.psm1

DSCResources/cChocoPackageInstall/cChocoPackageInstall.psm1

@@ -396,26 +396,15 @@ Function Upgrade-Package {
 }
 
 function Get-ChocoInstalledPackage {
-    $res = $null
     $PackageCacheSec = (Get-Date).AddSeconds('-60')
-    $childPath = 'ChocoInstalled.xml'
-    $ChocoInstallList = Join-Path -Path $env:ChocolateyInstall -ChildPath $childPath
+    $ChocoInstallList = Join-Path -Path $env:ChocolateyInstall -ChildPath 'ChocoInstalled.xml'
 
-    $lastWriteTime = (Get-Item $ChocoInstallList -ErrorAction SilentlyContinue).LastWriteTime
-
-    if ( $PackageCacheSec -lt $lastWriteTime ) {
+    if ( $PackageCacheSec -lt (Get-Item $ChocoInstallList -ErrorAction SilentlyContinue).LastWriteTime ) {
             $res = Import-Clixml $ChocoInstallList
+    } else {
+        choco list -lo -r | ConvertFrom-Csv -Header 'Name', 'Version' -Delimiter "|" -OutVariable res | Export-Clixml -Path $ChocoInstallList
     }
-    if (-not $res){
-        $res = choco list -lo | ForEach-Object {
-            $Obj = $_ -split '\s'
-            [pscustomobject]@{
-                'Name'    = $Obj[0]
-                'Version' = $Obj[1]     
-            }
-        }
-        Export-Clixml -path $ChocoInstallList -InputObject $res
-    }
+
     Return $res
 }