create methods for server collections when connection is null

Let server collections created with `new Meteor.Collection( 'someName', {connection: null} )` be used from client just like other collections.  Currently the server does not have insert, update, upsert, and remove methods created if the collection is null so calling them from the client will fail.

With this pull request, allow / deny rules still need to be set up for the collection or client calls will still fail just with the 'access denied' error instead of 'method not found' but this is inline with how other server collections work.