Improve first time data capture for memcached buckets

We currently do not have sufficient data capture in cbcollect_info to be able to debug issues with memcached buckets.

This MB is tracking improvements to cbcollect_info to allow us to more efficiently debug memcached bucket issues.

Assigned to David Haikney to flesh this list out, but a few ideas off the bat:

• cbstats items
• cbstats slabs