Proposed api for ChangeMonitor

ChangeMonitor.js

import ChangeMonitor from 'ChangeMonitor';

ChangeMonitor.registerDiffEngine('bookshelf', (m1, m2) => {
  /* diff the two objects */
  return { field: [previousValue, currentValue] };
});

ChangeMonitor.registerHandler('user', 'name', (user, previousValue, currentValue) => {
  console.log(`user name is now ${steve}`);
}, { diffEngine: 'bookshelf|objection|javascript|custom' });

ChangeMonitor.registerHandler('user', 'address', (user, previousValue, currentValue) => {
  console.log(`address is now ${address}`);
});

const user = await userService.getAUser();
const instance = ChangeMonitor.getMonitor('user', user);

user.name = 'Steve';

instance.commit(user);