Add transaction skeletons for: * revoke * namespace preorder * namespace reveal * namespace ready
Add transaction skeletons for:
* revoke
* namespace preorder
* namespace reveal
* namespace ready

Also, modify preorder and renew to append the STACKs to burn if the name's cost is priced in STACKs.
In addition, provide a class for encoding namespace rules.

blockstack/opendig,blockstack/blockstack-cli,blockstack/blockstack-cli