Error creating a DS when Riak is down or has issues.

If a CDN has DNSSEC enabled and you create a delivery service for that CDN, DNSSEC keys are created as part of the DS creation process. If Traffic Ops runs into an error with this process two things happen: 1) The delivery service is created but the DNSSEC keys are not and 2) instead of a user-friendly error message, the user is presented with a stack trace.
Traffic Ops should be updated such that 1) If an error occurs trying to create a DNSSEC keys for a new DS, the DS should not be added to the database and 2) the user should be presented with a user friendly message that lets them know an error occurred.