Cryptoissues? (stocks & bonds)
There are a couple that may be what your looking for.....

Open Transactions - http://opentransactions.org/wiki/index.php?title=Main_Page
This is more general and not specifically targeted at Cryptocurrency, it seems pretty malleable and could be used for what you are describing. 

https://counterparty.co/ - This is similar to above, and as I have only just recently found it cant say much, but also looks to do the job.