CF-165/CF-290: add wadl

Add the preferences-service WADL. @bwtaylor, @ChandraAddala, @usnavi, please review. 

I plugged the WADL into my Repose running on iNova. It was able to forward the request to the service.
That's the /metadata/{resourceName} &lt;resource&gt;.

But we have another resource that is actually fetching those resources. I don't think I could add this:
```
<resource id="archive_prefs" path="{resourceName}">
```
So for now, we have to build a WADL that's less dynamic. When we add a new resource, we have to edit the WADL.