Rearrange DataType enumeration and Refactor type systems

This patch rebuilds DataType enumeration and refactors type systems for more efficiency and extendibility of type. In detail, it does as follows:

• Remove the array return value from EvalNode, all functions, and Catalog.
  • Now, all operators, functions, and expressions return only one data type.
  • Instead, a data type can be array.
• Add Type.PROTOBUF type that enables Tajo to use a protocol buffer class as a type.
• Remove ArrayDatum and Type.Array which are used in some functions, requiring return two or more values.
  • Instead, they use generated protobuf type as return types.
• Add more rich data types to DataType.Type.
• Add ProtobufDatum and ProtobufDatumFactory that help create Builder with only a data type.
• Cleanup Catalog and many others.