[/diag/eval only] Disable bucket reload when configuration changes are made

Given the addition of the GIO and bucket priority in 3.0, I would like to ask that we disable ns_server's forced reload of the bucket when the following items are changed (and therefore allow them to be changed if they cannot currently):
-GIO thread count
-Bucket IO priority
-ejection policy

These are very frequently tuned items by the field, support and customers and it would be extremely helpful to allow the new values to be "set" but not yet applied until either a memcached restart occurs or a new node is balanced in. This is especially applicable for customers who are upgrading from a release that did not have these tunables and would want to change them after upgrading.

It would also be appropriate to display a warning message that the changes would not take effect until all nodes are either restarted or rebalanced out and in again.