Add distribution queue.

Queued distributions are still treated like un-queued ones, since currently
only 8 distributions are un-queued.  'View Distributions', however, will only
show un-queued distributions.

If an admin tries to remove a distribution with associated test results, an
error is printed and no action is performed.  This could be improved in the
future by showing a 'move test data' link.

include/sidebar_admin.php

@@ -30,6 +30,9 @@ function global_admin_menu() {
             BASE."admin/adminBugs.php");
     $g->add("View Test Results Queue (".testData::getNumberOfQueuedTests().")",
             BASE."admin/adminTestResults.php");
+    $g->add("View Distribution Queue (".distribution::objectGetEntriesCount(true).")",
+            BASE."objectManager.php?sClass=distribution&bIsQueue=true&sTitle=".
+            "Distribution%20Queue");
 
     $g->addmisc(" ");
     $g->add("Users Management", BASE."admin/adminUsers.php");