Cache URL Prefix
The URL prefix method was taking about 500ms on each run. This shouldn't
change often (at all?), especially not during a user session on vmenu.
It is cached for one hour. I also moved the call out so it is only called
once when fetching resources instead of once for each resource.
Add Names to Evernote Trace Statements
Some of the Evernote methods have a __name__ of delegate_method.
This doesn't help debugging. This change makes use of tracen in
those cases.