Add iceBerg query, cohort profiling and RelationalAlgebra

[KimballCai]

1. Add IceBerg query executor. aggregator, result parser.
2. In core/cohort/QueryResult, add error status.
3. In core/io/readstore, add logs
4. in core/io/readstore/FieldRS.java and CoolFieldRs, add getFieldType
5. In schema/TableSchema, add getFieldSchema and error check
6. In functionality, add CohortProfiling, IceBergLoader, RelationalAlgebra.
7. Update ReadME
8. Add olap-tpch dataset generation scripts and files

[KimballCai]

For details, please check pr#20