return errors before response for batch_write_incremental

preparation for making coherent return of db op responses

RUBY-676
bulk API comprehensive return value or exception - errors and exchanges

RUBY-676
Merge branch 'gjmurakami-10gen-1.x-stable-ruby-676' into 1.x-stable
write command fixes for special fields and :w symbol value

fix command with bson grow and query_contains_special_fields?

fix :w symbol value

RUBY-676
Merge branch 'gjmurakami-10gen-1.x-stable-ruby-676' into 1.x-stable