Integrate CBGT for DCP sharding - issue #922

[tleyden]

No description provided.

[adamcfraser]

Can we reuse our bucket.getDcpAuthHandler() here to do the username="" handling?

[adamcfraser]

Looks good to me - just a few minor items/questions.

[tleyden]

@adamcfraser I made the changes, one of which required a fairly intensive refactor to move the SequenceClock into the base package.

I made the SyncSequenceClock.Clock field exported, since it was being accessed directly from kv_change_index.go:

// Returns the stable sequence clock for the index
func (k *kvChangeIndex) getStableClock() base.SequenceClock {
    return k.stableSequence.Clock
}

We could approach this differently, it felt a bit kludgy .. maybe keep it unexported and add an ExportClock() method?

Currently left as separate commits for easier viewing, will squash before merge.

[tleyden]

Dev build passed:

http://mobile.jenkins.couchbase.com/view/Sync_Gateway_Dev/job/sync-gateway-dev-build/261/

Ready for merge