Add a local flag that can prevent the adapter from publishing the emi…

[tal-beja]

…t to the server

[tal-beja]

Works with this pull request:
socketio/socket.io#2628

[darrachequesne]

@tal-beja hi! May I ask what your use case is please?

[tal-beja]

When several insrances of a server recieve the same even from a third party (not from a client), each server instance broadcast the event to all his clients.
If I use the redis adapter each server publish to redis about the event and thus each client recieve the same event times the number of the server instances.
With the local flag, and the change in the redis adapter, each server instance send the event only to his client, so each client recieve only one uniqe event.

[darrachequesne]

@tal-beja sorry for the delay. Could you please rebase and add some tests please?

Also, is the redis version bump mandatory for this to work? Do you know what the impact is? (the changelog seems huge, especially towards the pub/sub mechanism)

[KristjanTammekivi]

bump

[17289kjhajshd389210h]

+1 @tal-beja

[darrachequesne]

Merged as c38e323. Thanks!