Decoupling the Supermarket from the Market

[elpiel]

Since the Supermarket is very dependant on the Market to retrieve the campaigns, it makes the Supermarket work quite obsolete (apart from safety & performance). This is why we want to make the changes to decouple it from the Market and instead fetch the campaigns from the validators in a configured list .

Changes:

1. [x] PR #24 Configuration list of validators to fetch the campaigns from (instead of the market)
2. [x] PR #24 Fetch the active (channel.valid_until > Now) campaigns (and compute their status)

TODOs:

• [x] ~Check ChannelId when Channel is fetched from Validator:~ This is not really required since the get_status will check both validators and if they don't agree a bad status will be returned https://github.com/AdExNetwork/adex-validator-stack-rust/blob/dev/adapter/src/ethereum.rs#L162-L173
• [x] Test Cache::update & Cache::fetch_new_campaigns (after initialization)

The flow stays the same:

• :heavy_check_mark: On start-up initialize the Cache by querying each validator for Channels and compute the Status - repeat every couple of minutes
• :heavy_check_mark: Compute the latest status by querying the Leader/Follower for latest messages - repeat every couple of seconds

[elpiel]

Closing issue as all tasks are solved.

This is not really required since the get_status will check all validators and if they don't agree a bad status will be returned:

Check ChannelId when Channel is fetched from Validator: https://github.com/AdExNetwork/adex-validator-stack-rust/blob/dev/adapter/src/ethereum.rs#L162-L173~