ZP-1039 Don't use die() to terminate in error case for z-push-admin.

Released under the Affero GNU General Public License (AGPL) version 3.

src/z-push-admin.php

@@ -75,7 +75,8 @@ include_once(ZPUSH_CONFIG);
         ZPushAdminCLI::RunCommand();
     }
     catch (ZPushException $zpe) {
-        die(get_class($zpe) . ": ". $zpe->getMessage() . "\n");
+        fwrite(STDERR, get_class($zpe) . ": ". $zpe->getMessage() . "\n");
+        exit(1);
     }