We would like to remind everybody that on August 31, 2016, we are deprecating two DFP API versions at the same time in an effort to tighten our deprecation schedule.
This means that if you are currently using v201508 or v201511, you should look into upgrading to the latest DFP version now.
You can find our full deprecation schedule on our developers site. We also encourage you to join our sunset announcement mailing list.
As always, if you have any questions, feel free to drop us a line on the DFP API forums or the Ads Developer Google+ page. 
- Vincent Tsao, DFP API Team