executor: remove `Base` arg from model function

Simplify the contract for functions exported by `models/*.js` files
by removing the second argument `Base`. The base class can be accessed
using `ModelCtor.base` (a feature introduced in strongloop/loopback-datasource-juggler#179).

An updated example of a model js file:

```js
module.exports = function(Customer) {
  Customer.setup = function() {
    Customer.base.setup.apply(this, arguments);
    // etc.
  };
};
```

The first commit which updates dependencies is not related to this change.

/to @raymondfeng please review
/cc @ritch