WiFi -> Cell while in the background

[geremyCohen]

We've discovered a connectivity issue on iOS. It is a possible hang when switching from WiFi to Cell while the app is in the background.

The patch is available here: https://github.com/pubnub/objective-c/tree/hotfix-t191
This patch is forked off the existing 3.5.1 release, and has been tested.

We are currently assembling our 3.5.2 release, estimated for release by end of next week, which will contain this fix, and other enhancements as well.

geremy