Use cascading.tuple.Tuple's getObject method instead of get.

The latter is deprecated and does a cast to java.lang.Comparable which
means that some data types can not be used with Maple's
JDBCTap (e.g. primitive arrays, org.postgresql.util.PGObject, etc).
Merge pull request #48 from screen6/develop

Use cascading.tuple.Tuple's getObject method instead of get.