Kindle Fire HDX Support

Adds support to properly parse device family for the 3rd generation Kindle Fires.

http://docs.aws.amazon.com/silk/latest/developerguide/user-agent.html

Kindle Fire HD 7" (3rd Generation)–KFSOWI
Kindle Fire HDX 7" (3rd Generation)–KFTHWI
Kindle Fire HDX 7" (3rd Generation) 4G–KFTHWA
Kindle Fire HDX 8.9" (3rd Generation)–KFAPWI
Kindle Fire HDX 8.9" (3rd Generation) 4G–KFAPWA