Overview page formatting

Really just a nitpick, but two things I've noticed on the overview page:

1. package names use /, i.e. groovy/grape rather than dot notation
2. The package description summaries are surrounded by a <p> tag, which makes each table row very tall (if you look at the class-summary tables, they just have text directly inside the <td>, no enclosing <p> tag.)

Thanks! The groovydoc improvements look great Paul.