Merge pull request #315 from shirioko/master

Added contact sync v2
Fixes issue of Accessing static property WhatsApEvent::$event_callbacks as non static
Merge branch 'master' of https://github.com/venomous0x/WhatsAPI.git
Merge branch 'master' of https://github.com/shirioko/WhatsAPI.git into pollmessagefix
Added new WaitforServer() function to ensure server has received and responded to sending messages/updating status etc.

This is NOT the same as waiting for a delivery receipt. The other handset could be offline and so you may not receive that notification for hours...
Merge pull request #1 from jonnywilliamson/master

Create a waitforserver function to ensure request is processed