Small fixes for anon_community, don't connect to trackers.
Implemented is_key_compatible is_candidate_compatible which makes sure
that my_member and candidate/key are using the same elliptic curve.
If not, we don't connect/extend etc to them.
Merge pull request #597 from NielsZeilemaker/small_fixes

Small fixes for anon_community, don't connect to trackers.