Defined Shark's own TableDesc and ColumnDesc class, so Shark's Scala and Java APIs no longer
expose Hive internal data structures.
Disable exceptions for unknown data types. This is needed because we don't support complex data types yet.
Properly handle limit in SharkContext and added APIs for getting complex types in Row.
Updated SQLSuite to use executeSql.
Merge branch 'master' of github.com:amplab/shark into api
More APIs update.

- runSql now also runs DDL commands.
- moved DataType into a top level class in api package.
Made runSql function work for DDL commands.
Merge pull request #111 from amplab/api

Shark Scala API update