(gh-181) Add Chocolatey helper module

Add Chocolatey helper module as a placeholder for utility funcitons to
assist in the prodcution of Chocolatey packages.  In the first instance a
helper function to retrieve a redirected url has been added.

scripts/chocolatey-helpers/functions/Get-RedirectedUri.ps1

@@ -0,0 +1,59 @@
+Function Get-RedirectedUri() {
+  <#
+    .SYNOPSIS
+      Get the uri that is being redirected to when using the supplied uri parameter.
+
+    .DESCRIPTION
+      Get-RedirectedUri is a Powershell function to obtain the URI that is being redirected to from the supplied URI.
+      The URI to obtain the redirection for is specified using the Uri parameter.  The redirected URI will be returned
+      or the supplied URI if no redirection has taken place.
+
+    .PARAMETER $Uri
+        The URI to obtain the redirection for
+
+    .EXAMPLE
+        PS C:\> Get-RedirectedUri -Uri 'https://download.mozilla.org/?product=firefox-latest&os=win64'
+
+        Obtain the redirected URI for the Windows 64-bit Mozilla Firefox download.
+
+    #>
+  [CmdletBinding()]
+  Param(
+    [parameter(Position = 0,
+      Mandatory = $true,
+      ValueFromPipeline = $true,
+      HelpMessage = 'The Uri to obtain the redirection for')]
+    [ValidateNotNullOrEmpty()]
+    [String]
+    $Uri
+  )
+  process {
+    do {
+      try {
+
+        Write-Verbose('Attempting to retrieve URL redirect for ' + $Uri)
+        $response = Invoke-WebRequest -Method Head -Uri $Uri
+
+        if ($null -ne $response.BaseResponse.ResponseUri) {
+          Write-Verbose('Extracting redirected URI from BaseResponse')
+          $redirectUri = $response.BaseResponse.ResponseUri.AbsoluteUri
+        } elseif ($null -ne $response.BaseResponse.RequestMessage.RequestUri) {
+          Write-Verbose('Extracting redirected URI from RequestMessage')
+          $redirectUri = $response.BaseResponse.RequestMessage.RequestUri.AbsoluteUri
+          Write-Verbose('Redirected URL ' + $redirectUrl)
+        }
+        $retry = $false
+      } catch {
+        if (($_.Exception.GetType() -match 'HttpResponseException') -and ($_.Exception -match '302')) {
+          $Uri = $_.Exception.Response.Headers.Location.AbsoluteUri
+          $retry = $true
+        } else {
+          throw $_
+        }
+      }
+    } while ($retry)
+
+    Write-Verbose('Returning redirected URL ' + $redirectUrl)
+    $redirectUri
+  }
+}