Added 'throwaway' producer so we can test without Solr

To test:

1. Start Vagrant and SSH in 

    $ vagrant up
    $ vagrant ssh

2. Start up ZooKeeper and Kafka

    $ cd /usr/share/kafka/
    $ bin/zookeeper-server-start.sh config/zookeeper.properties &
    $ bin/kafka-server-start.sh config/server.properties &

3. Create a topic for documents (only needs to be done once):

    $ bin/kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 1 --topic documents

4. View the messages on the sample consumer:

    $ bin/kafka-console-producer.sh --broker-list localhost:9092 --topic documents

5. In a separate terminal on your host machine (not in the Vagrant vm) build the project (`mvn clean install`) and then run the producer:

    $ mvn -q -e exec:java -Dexec.mainClass="com.bloomberg.bask.stub.TweetProducer" -Dexec.classpathScope="test"