Minor code change due to Optiq 0.6-SNAPSHOT change.

Rename ConnectionConfig to DrillConnectionConfig due to optiq-0.6-SNAPSHOT add an interface with same name.

Signed-off-by: vkorukanti <venki.korukanti@gmail.com>
More minor changes due to Optiq 0.6-SNAPSHOT: 1. org.eigenbase.rel.Direction capitlization changes 2. DrillAggregateRel and DrillProjectRel interface changes 3. SqlExplain interface changes