Export LearningPackage Data in lp_dump

[dwong2708]

Description

As a continuation of issue #331, the export process for a learning package should now use real data from the LearningPackage model, rather than stub values currently used in the implementation.

Acceptance Criteria

• Give an error in the lp_dump command if the export process fails
• Export actual data from the LearningPackage model instead of stub values