Fix HadoopDruidIndexer to work with the new way of things

There are multiple and sundry changes in here.

First, "HadoopDruidIndexer" has been split into two pieces, (1) CliHadoop which pulls the hadoop version and builds up the right classpath with the proper hadoop version to run the indexer and (2) CliInternalHadoopIndexer which actually runs the indexer.

In order to work around a bunch of jets3t version conflicts with Hadoop and Druid, I needed to extract the S3 deep storage stuff into its own module.  I then also moved the HDFS stuff into its own module so that I could eliminate the dependency on Hadoop for druid-server.

In doing these changes, I wanted to make the extensions buildable with only the druid-api jar, so a few other things had to move out of Druid and into druid-api.  They are all API-level things, however, so they really belong in druid-api instead.

Lastly, I removed the druid-realtime module and put it all in druid-server.