Integrate chainlink feed
close #1056
@wangjj9219 @xlc request review, can't actually request review because it is your pr ;).
Reasonable initial integration of the pallet-chainlink-feed for testnet. I would say the chainlink pallet still needs a bit more work on the slashing mechanism for if an oracle is giving bad/malicious feeds (able to disable bad oracle but can't take awarded LINK).
Adds LINK token (unsupported in karura/acala) and new chainlink types that need to be added to acala.js
Should be fine but will take a closer look later. I don't want to merge until Acala genesis is ready.
What's the status of this PR?
It is on hold as waiting the chainlink pallet to be updated to latest Substrate version.