add browserify support to package.json
add browserify support to package.json

allowing `browserify` to be used directly against the `bson` library without requiring any special configuration
flyingfisher/js-bson,flyingfisher/js-bson,JacksonTian/js-bson,msmiley/js-bson,jkresner/js-bson,mongodb/js-bson,kevinsawicki/js-bson,mongodb/js-bson,mongodb/js-bson,timkuijsten/js-bson,msmiley/js-bson,JacksonTian/js-bson,kevinsawicki/js-bson,timkuijsten/js-bson,mongodb/js-bson,kevinsawicki/js-bson,kevinsawicki/js-bson,jkresner/js-bson