Change QueryResult to retain column value types

https://issues.cask.co/browse/CDAP-384
Since a Hive query result row only contains objects of primitive types, we define a new QueryResult.ObjectResult that holds the type and the primitive value.

Bamboo build: https://builds.cask.co/browse/CDAP-DUT114
One question is, how is this object get serialize and deserialize? Can we use a custom TypeAdapter? If that's the case, it can simply be a `ResultType` and a `Object value`.