implementation: follow-up to refactoring CMC spec

[alex-chew]

Follow-up for #166.

• C
  • Accept local CMC capacity values below 2: Accept local CMC capacity values below 2 aws/aws-encryption-sdk-c#562
• JavaScript
  • Accept local CMC capacity value of 0: Accept local CMC capacity value of 0 aws/aws-encryption-sdk-javascript#397
• Python
  • Accept TTL in local CMC's put_decryption_materials: Accept TTL in local CMC's put_decryption_materials aws/aws-encryption-sdk-python#285
  • Accept local CMC capacity value of 0: Accept local CMC capacity value of 0 aws/aws-encryption-sdk-python#289