Fix owner test
Encode seq before sending request

CouchDB 2.0 sequences are lists (of form [non_neg_integer(),
binary()]) where previously they were strings (either as binary or as
list) or numbers. The replicator calls iolist_to_binary on all
parameters which scrambles this new format.

Ensure we've JSON encoded the since value to a binary before calling send_req.
Use couch_log instead of ?LOG_*
Update handle_changes function names