webapp: put new repos in standard groups

I'm using transfer for most things, both removable drives and cloud
storage, because it's the safest choice. We'll see if it makes sense
to prompt for the group when setting this up, or let the user pick
something else after the fact.

Logs/PreferredContent.hs

@@ -25,10 +25,10 @@ import Logs.UUIDBased
 import Limit
 import qualified Utility.Matcher
 import Annex.UUID
-import Annex.Groups
 import Git.FilePath
 import Types.Group
 import Logs.Group
+import Annex.StandardGroups
 
 {- Filename of preferred-content.log. -}
 preferredContentLog :: FilePath