Search for myself upon starting up

#### Bug
In order to get all the peers in our network we have to call `search_for_my_node`. The code for this was already in `join_network`, however it was commented out because it didn't work. The reason for this is that `search_for_my_node` was called directly, before it was made sure that a handshake was completed with a seed.

#### Fix
Add a callback that runs inside the `ioloop` once every second, until a connected peer is found.