Bump version to 4.0.2
Bump version to 4.0.2

mongodb/bson-ruby,ukblewis/bson-ruby,estolfo/bson-ruby,mongodb/bson-ruby,estolfo/bson-ruby,ukblewis/bson-ruby,mongodb/bson-ruby,mongodb/bson-ruby,estolfo/bson-ruby,ukblewis/bson-ruby,estolfo/bson-ruby,ukblewis/bson-ruby