Fix various bugs in the seeder.
- fix fubared logs format
- Ensure that the main logger dump on the console just like the rest of the seeder does.
- Ensure connections to new nodes are etablished properly.
Test Plan: Run the seeder manually, ensure it starts crawling the network and that the log look much better.
Reviewers: #bitcoin_abc, Fabien
Reviewed By: #bitcoin_abc, Fabien
Subscribers: Fabien, teamcity
Differential Revision: https://reviews.bitcoinabc.org/D2113