serve: provide basic entry point

Hi, this is for people to look at... I'm not quite sure how people expect to use Serve. At least, this seems to do something vaguely useful.... (I'll file a bug if people are interested in this code). There's no styling -- I'm not a big style person...

Index:
* List included platforms (and available platforms)
* List included plugins
* List package name, id, version

* Provide directory redirects
* Implement directory browsing