this patch has no behavior changes, changes are:
* server.Datastore() -> server.datastore
* server.MQ -> server.mq
* server.LogDB -> server.logstore
* server.Agent -> server.agent
these were at a minimum not uniform. further, it's probably better to force
configuration through initialization in `server.New` to ensure thread safety
of referencing if someone does want to modify these as well as forcing things
into our initialization path and reducing the surface area of the Server
abstraction.
