load_state does not await bootstrap

[JohnDoee]

Describe the bug
When trying to load_state, the bootstrap promise is never awaited and therefore the function won't work. https://github.com/bmuller/kademlia/blob/master/kademlia/network.py#L224

This brings up a bit of weirdness for me because I don't find it smart to save state that way. My solution was to save the whole routing table.

[bmuller]

Thanks @JohnDoee - another great catch.

Btw - just loading the bootstrappable neighbors should be sufficient to rebuild the routing table (with up to date routes - it's possible many nodes you knew about before are no longer active/up).