* Refactor Enroll HTTP Handler factory
* Begin `crypto` package
* Implement OTA enroll profile endpoint
* Implement Handlers, Endpoints, and encdecs for OTA Phase 2 & 3
* Implement certificate verification against Apple Device CA
* Implement Phase 2 & 3 logic based on provided CMS cert
* Provide (existing) enrollment profile on Phase 3
* Implement SignMessage handling to verify client SCEP certificate (#118)
* Add a TODO, fix-up some sloppiness
* Use direct CN plus serial number query rather than looping over existing CNs