Updates model and tests to newest bitcore version

- updates models and tests to newest bitcore version
- temporary link bitcore using:
        "bitcore": "git://github.com/bitpay/bitcore.git#1b37d88e9a1d651c2b1d0552c5e8698a0eeefb9c",
en package.json

test pass in node and browser. 

Manual testing is fails: after hitting 'sent' in a transaction proposal, it throws:
Uncaught TypeError: Cannot read property 'toString' of undefined 
on the js console.