[FS#680] Outdated nft version

[LEDE Bugs]

The following task is now closed:

FS#680 - Outdated nft version
User who did this - Yousong Zhou (yousong)

Reason for closing: Won't fix
Additional comments about closing: master branch now has nftables 0.7.  This is not likely to land in LEDE-17.01 though.

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=680