Add a new constructor and mark the constructor with the useUpsert attribute directed
Merge branches 'master' and 'master' of github.com:sspinc/mongo-hadoop

* 'master' of github.com:sspinc/mongo-hadoop:
  Fix usage of MongoInsertStorage and update description
  Fix usage of MongoInsertStorage

* 'master' of github.com:sspinc/mongo-hadoop:
  Fix usage of MongoInsertStorage and update description
  Fix usage of MongoInsertStorage