RUBY-1115 Only add write concern to index operations if server >= 3.4
RUBY-1115 Only add write concern to index operations if server >= 3.4

estolfo/mongo-ruby-driver,saghm/mongo-ruby-driver,mongodb/mongo-ruby-driver,kay-kim/mongo-ruby-driver,jonhyman/mongo-ruby-driver,estolfo/mongo-ruby-driver,saghm/mongo-ruby-driver,mongodb/mongo-ruby-driver,jonhyman/mongo-ruby-driver,mongodb/mongo-ruby-driver,kay-kim/mongo-ruby-driver