Update Chapter 03 for more recent versions of Pig, Hadoop, and Mongo-Hadoop.

These changes allow for using more recent versions of Pig and Mongo-Hadoop. Selecting and configuring the best software versions can be very confusing for the beginner. If the reader has already installed Hadoop 2.0.x, but doesn't specify that when building Pig then he'll get "missing class" errors when running pig/sent_counts.pig. AvroStorage has moved from Piggybank to Pig. MongoStorage has changed.