Created a new base value ScatterGatherValue that extends Value. 
Modified variable length values (BinaryValue, CodeableValue and
StringValue) inherit from the new base class.
Merge branch 'master' of github.com:jpercent/catena
Merge branch 'master' of github.com:jpercent/catena into predicate-pushdown
Added ArrayDescriptor.Sizes.  Class for traversing an array elements.
Improved size traversal code
Added scala and fixed avro version