hg serve: call setconfig on the parentui
It makes sense to do this on the "global" ui object, since command line
options should affect the whole process.
This should fix hg serve --style=gitweb inside a repo (part of issue253).
Content-type: text/html; charset={encoding}
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<link rel="icon" href="#url#static/hgicon.png" type="image/png">
<meta name="robots" content="index, nofollow" />
<link rel="stylesheet" href="#url#static/style.css" type="text/css" />