Stat improvements for View queries.

Currently the only way to work out what types of queries are being made against a node is to parse ns_server.couchdb.log. While this has all of the information about the query, the log does rotate quick and in some case we only have a few hours of information.

In the last few support cases Engineering has asked is this the "normal number of stale=false" query for this customer. Unfortunately we could not answer that question. In the same case we were also asked what is teh average

It would be useful if we have the following stats in the ETS tables for the views:

• Number of stale=false queries
• Number of stale=ok queries
• Number of stale=update_after queries
• Network bytes written to client request
• Network bytes written to Server requests

It would also be useful to have timing stats, how long it took to service the requests from the client and the other Couchbase nodes

I more than happy to break this MB into sub-task.