#27: ComparatorTypes now accepts 'reversed' qualifiers.

- ComparatorTypes now accepts 'reversed' qualifiers for both simple and
composite types.
- Added unit tests to cover these new features.
- Added integration tests to cover these new features.

See also: https://github.com/jsevellec/cassandra-unit/issues/27

Signed-off-by: Marc CARRÉ <carre.marc@gmail.com>