Hadoop profiles

Refactored the pom.xml to incorporate the usage of profiles allowing building with different versions of Hadoop.  Similar to Spark, the Maven command line now ends up looking like:

  mvn -Phadoop1 package

or

  mvn -Phadoop2 package

Except for a bump of the log4j version, the hadoop1 profile builds exactly the same configuration as the pom.xml did before this PR.