Sola referral program term changes

We have doubled the reward to attract quality users who actively use Sola and create value for the community. 5 SOL bonus for signing up and a referral registration is removed.

Here are the new terms that are in effect right now:
- You receive 10% of all SOL earned by all referred users (twice as much as before);
- You receive +100AP for each referral registration;
- You receive +1AP for each click on the link (up to 50AP per link)