Migrating Nodequeue to D8

Since the Drupal 8 API are frozen now i think to we are in a good place to start to migrate nodequeue to D8.

I already started to work on this: https://drupal.org/sandbox/gnuget/2048117

This work is still in a too early stage but before to continue working on it i want to clarify some details about the actual status of the 7.X version of the module.

• Actually exists a 7.x-3.x branch, should i start to porting to D8 from this branch instead of from the 7.x-2.x branch?
• Seems to the 7.x branch not have test cases #468136: Nodequeue: Add test cases, This tests would be very helpful for have a test base for start to test the D8 version. But i'm not sure if the lack of tests could be considered as a block for the process to migrate to D8