Addresses tickets EDU-314, EDU-202, EDU-217. Provides an AWS Lambda function which receives edX events from Segment, and performs the following:

• problem_check: remaps fields that have GUID type IDs in them to not have those in, adds a new field block_id containing the problem block ID, pushes a new event back to Segment called a redisu.problem_check event. problem_check events in Segment no longer go direct to Redshift, they go to this Lambda. redisu.problem_check events do now go to Segment.
• edx.course.enrollment.activated: remaps field context.referer to the top level, breaks out any referer URL to add new fields for mkt_tok, utm_source, utm_medium, utm_campaign
• edx.certificate.created: remaps field data.certificate_id to the top level

The Lambda can also additionally serve as a debugging location for the new events it creates. If Segement is configured to send any of the following events to it, the Lambda will simply log the payload:

• redisu.problem_check
• redisu.certificate.created
• redisu.course.enrollment.activated

When deploying this, the Lambda needs one environment variable set. This is SEGMENT_WRITE_KEY which should contain the Segment write key that it uses to create new events.