Drupal 8 Entity Field API completion

With the release of Drupal 8 nearing, the Entity & Field APIs are nearing completion as well. But that does'nt mean there aren't lots things to do left - see the meta issue for a status update. So if you wanted to get into the new APIs, this is your opportunity! We need people to help implementing updating patches, reviewing code changes, writing tests, etc. Please do sign up for the sprint so know how many people to expect when!