Nicks with non-alphanumeric values stripped. All chars are downcased.

--HG--
rename : memberizer/test/test_members-2.json => memberizer/test/test_members_edgecases.json
Members without nicknames are now skipped.
Sends emails when processing of members doesn't end well. Sends it to the fingerprints in "emerg_notifiers" and the signer (if that was available).