Switch CIS to the Cryptography SDK

[andrewkrug]

Cryptography SDK is preferred to our method of data key encryption.

Let's find a way to use this instead. ( See pykmssig for example )

[andrewkrug]

• [ ] Refactor the CIS Core
• [ ] Refactor the testing
• [ ] Deploy change to CIS_Functions and mozillians staging
• [ ] File CAB
• [ ] Deploy change to CIS_Functions and mozillians production