Crypto Conditions Draft 3

Hi all,

Please find draft 3 of the Crypto-Conditions spec attached.
Changes include:
- Some clarity on URI format
- Some editorial fixes

Unfortunately the IETF tool for submitting IDs is closed while IETF 99 is
running so I can only submit this on Monday.

This does mean the draft will expire for 2 days, apologies for the
inconvenience.

Adrian