CHOP-102. Scripts automatically import scalding and Express.

issue: https://jira.kiji.org/browse/CHOP-102

Reviewed by: kiyan
CHOP-68. Ensure resources are closed properly in tutorial code.

This commit modifies the importers and top next songs producer to
use doAndRelease when creating entity ids, not retainAnd. This
ensures all resources are closed properly.

This commit also iterates the express dependency version to 0.2.0-SNAPSHOT.

Reviewed by: robertchu