Known Dialyzer warning

[lucafavatella]

Dialyzer warning as detected by OTP 19.2 on e502d3a (by Travis CI):

sumo_store_riak.erl:490: The call sumo_store_riak:update_map(Conn::pid(),Bucket::{binary(),binary()},'undefined',{'map',[{{binary(),'counter' | 'flag' | 'map' | 'register' | 'set'},_}],[{{binary(),'counter' | 'flag' | 'map' | 'register' | 'set'},_}],[{binary(),'counter' | 'flag' | 'map' | 'register' | 'set'}],'undefined' | binary()},Opts::['if_none_match' | 'if_not_modified' | 'return_body' | 'return_head' | {'dw','all' | 'default' | 'one' | 'quorum' | non_neg_integer()} | {'n_val',pos_integer()} | {'pw','all' | 'default' | 'one' | 'quorum' | non_neg_integer()} | {'sloppy_quorum',boolean()} | {'w','all' | 'default' | 'one' | 'quorum' | non_neg_integer()}]) will never return since it differs in the 3rd argument from the success typing arguments: (pid(),{binary(),binary()},binary(),{'map',[{{_,_},_}],[{{_,_},_}],[{binary(),'counter' | 'flag' | 'map' | 'register' | 'set'}],'undefined' | binary()},[atom() | tuple()])

This Dialyzer warning fix depends on riak-erlang-client spec fix.

See #12 (comment) and following for context.

[lucafavatella]

Upstream fixed. New tag requested.

[lucafavatella]

New tag taken by upstream. Testing now.