handle upgrades by taking over the database

[kletkeman]

Depends on: hyperledger/fabric#1217

We need to be able to upgrade a contract, which of course would be the default behavior in all new version of a contract upon execution of Init().

Each new version will have to implement whatever data migration will be necessary, but by storing data as JSON objects, and by maintaining original JSON tags, we can alleviate the vast majority of data migration requirements.

[kletkeman]

Fabric v1 allows chaincode to be named during deployment, so this is no longer much of an issue. As in, one need only follow best practices for JSON databases to be able to upgrade chaincode and redeploy without difficulty. Do note, though, that fabric v1 introduces a versioning mechanism that is separate from the mechanism we use in our own contracts. I am closing the issue because there is nothing here to implement or fix.