Generate source code inventory

[katucker]

User Story

As a Source Code Inventory manager, I want to generate a file containing current source code repository metadata so that I can publish a source code inventory to promote reuse.

Acceptance Criteria

Upon selecting the feature to generate an up-to-date source code inventory, a file named code.json is generated, compliant with the schema described on the code.gov website. The file contains current metadata for every source code repository approved for publication in the inventory.