This commit sets a cluster ID when the first node is initialized.
The ID is generated on every CreateNodeCommand so that it can be
applied consistently in the state machine of every server.
This commit moves meta data from the influxdb.Server and extracts it
out to a new "meta" package. This package handles all strongly
consistent data in the database and maintains a small set of metadata
in-memory.
Conflicts:
meta/store.go