Moved buckets (plural) into a separate file.
Refactored bucket loading to separate individual from batch.
errors.New(fmt.Sprintf(a, b)) -> fmt.Errorf(a, b)
Initial implementation of automatic bucket passivation.

Primarily, you get not-my-vbucket errors when the client stops
talking.  The connection holds a defunct bucket reference directly, so
when the bucket closes, the server doesn't know, and it doesn't know
which bucket it had open so it can't reconnect.

This can be solved, but it's sort of future commit status.

cbugg: close bug-472
Don't need that much code to copy a struct.
Report slow view requests.
Remove some connection logging.
Web UI serves NS static assets and NS api on port 8091.

Instead of mushing couchDB REST api and NS REST api into one port
(8077), the NS REST api (and NS static assets) are now served by
default via -rest-ns=:8091 cmd-line parameter.

NS static assets are from couchbase/ns-server: 2.1r-133-gde0aa5a
REST ns api /versions implemented.
Provide couchApiBase on separate port.
More progress towards subset of NS web UI.
REST ns api implement thisNode flag.
REST ns api for LocalRandomKeyURI.
Repeated mux path for couchDbGetDb().
REST ns api emits X-Couchbase-Meta header.