metrics: new DB metric representation

Going off of Bill Kayser's recommendations, rework the MongoDB and MySQL
metric names (and metrics recorded) to match the new, more general DB
parameter names.
test: versioned -> multiverse
metrics: renamed Redis metrics to match new spec

Seems like once memcached is cut over to this, the metrics recording
gets more generic.
metrics: renamed memcached metrics to match new spec

This is all starting to look a lot more consistent.
metrics: record{Redis,Memcache} -> recordDatastore

The only reason MongoDB isn't in here is because it has statement-level
metrics.
metrics: add instance metric for MongoDB

Also set up segment infrastructure for carrying around that information.
metrics: add instance metric for MySQL

Exposes the sorry state of the MySQL tests that this patch is so short.
metrics: add instance metric for Redis

Had to de-unify recordDatastore, but it's simple and fast even if it's
now duplicate boilerplate. Surprisingly simple!
metrics: add instance metric for memcached

...but only in the case when the driver has a connection to only a
single node, as otherwise it's too hard to figure out what shard a given
key was fetched from.
deps: updated to newest version of CLS
deps: updated to use latest CLS / async-listener

Meant to nail down error-handling issues seen by 0.8.x users.
Merge branch 'othiym23/db-metric-renaming'

Already deployed to RPM. Just need Node piece.
docs: updated for new version
release: 0.12.0 - updated deps and Datastore metric names