Make advance interval adaptive to differentiate from polling

[narinearraul]

tmpreiss commented on May 9, 2016
Currently the iOS and Node (and Android?) SDKs will issue an advance request to the server -- for each ACL the user has read access to -- at least every 5 seconds.

This is not significantly different from polling.

The SDKs should implement an intelligent backoff strategy for advance requests that incorporate events such as app connect/disconnect and app foreground/background to reduce advance traffic so as to differentiate from polling.