Merge c2s and resolver into one component

Ref. #109

Pros:
* no more "remote" authentication
* presence can be looked up immediately
* no race conditions/sync issues between c2s and resolver
* much easier presence takeover and load balancing

Cons:
* no more resolver route (backwards incompatibility)
* domain kontalk.net will be handled by c2s
* much bigger and complex component (despite, modularization can help)

Tasks currently delegated to the resolver:
- [ ] fingerprint verification for login
- [ ] vCard requests/public key storage
- [ ] presence data cache (use external key/value database?)
- [ ] presence data/public key network broadcast
- [ ] stanza authorization