Add More bullets to what is different from JOSE
Change the indexes used by msg_type so that zero is not used.
Allow for signture payloads to not be present.
Expand the text on keys
Add CBOR encoder restrictions - not sure if this is complete or not - see open issue
Add IANA and Security considerations place holders.
Merge pull request #21 from jimsch/master

Add More bullets to what is different from JOSE