RBR was not considering the option --slave-skip-errors.
                              
To fix the problem, we are reporting the ignored ERROR(s) as warnings thus avoiding 
stopping the SQL Thread. Besides, it fixes the output of "SHOW VARIABLES LIKE 
'slave_skip_errors'" which was showing nothing when the value "all" was assigned 
to --slave-skip-errors.
                  
@sql/log_event.cc
  skipped rbr errors when the option skip-slave-errors is set.
@sql/slave.cc
  fixed the output of for SHOW VARIABLES LIKE 'slave_skip_errors'"
@test-cases
  fixed the output of rpl.rpl_idempotency
  updated the test case rpl_skip_error