Update contributors scripts to do more stuff

Tools/dump_commits_since.ps1

@@ -6,16 +6,22 @@ param(
     [Parameter(Mandatory=$true)]
     [DateTime]$since,
 
+    [Nullable[DateTime]]$until,
+
     [Parameter(Mandatory=$true)]
     [string]$repo);
 
 $r = @()
 
 $qParams = @{
-    "since" = $since.ToString("o")
+    "since" = $since.ToString("o");
     "per_page" = 100
 }
 
+if ($until -ne $null) {
+    $qParams["until"] = $until.ToString("o")
+}
+
 $url = "https://api.github.com/repos/{0}/commits" -f $repo
 
 while ($null -ne $url)