Make LiftRules use the html5 parser by default

Right now we have this in LIftRules:

```scala
val htmlProperties: FactoryMaker[Req => HtmlProperties] =
new FactoryMaker(() => (r: Req) => (new OldHtmlProperties(r.userAgent): HtmlProperties)) {}
```
let's change it to use
```scala
(r: Req) => new Html5Properties(r.userAgent)
```