The DatastoreConfig discovery type is unused. Remove the constant and
any resulting dead code. Today's biggest loser is the IPAM Allocator:
DatastoreConfig was the only type of discovery event it was listening
for, and there was no other place where a non-nil datastore could be
passed into the allocator. Strip out all the dead persistence code from
Allocator, leaving it as purely an in-memory implementation.

There is no more need to check the consistency of the allocator's
bit-sequences as there is no persistent storage for inconsistent bit
sequences to be loaded from.

Signed-off-by: Cory Snider <csnider@mirantis.com>

Signed-off-by: allencloud <allen.sun@daocloud.io>

With this change, all the auto-detection of the addresses are removed
from libnetwork and the caller takes the responsibilty to have a proper
advertise-addr in various scenarios (including externally facing public
advertise-addr with an internal facing private listen-addr)

Signed-off-by: Madhu Venugopal <madhu@docker.com>

Signed-off-by: Santhosh Manohar <santhosh@docker.com>

Signed-off-by: Alessandro Boch <aboch@docker.com>

Signed-off-by: allencloud <allen.sun@daocloud.io>

Signed-off-by: Alessandro Boch <aboch@docker.com>

- Move DiscoverNew() and DiscoverDelete() methods into the new interface
- Add DatastoreUpdate notification
- Now this interface can be implemented by any drivers, not only network drivers

Signed-off-by: Alessandro Boch <aboch@docker.com>