Add GenerateEvents.java to populate events table created via CLI

With an eye toward modularization, I've repurposed CreateEvents.java from the Spark example and placed it in org/kitesdk/examples/data. This lets the customer create the events dataset using the CLI, then populate it with a substantial number of records using the Java utility. The same dataset can be used for the Flume and Spark examples, without having to delete them after running their respective jobs.

In GenerateEvents, I essentially swapped the CreateEvents create() method with load(). I added the Avro plug-in to pom.xml, copied the avro folder with standard_event.avscinto the main directory, and copied BaseEventsTool.java to org/kitesdk/examples/data.

In my environment, it compiles, runs, and populates the events table as expected.