Logger available in modules

This simple module throws an error when it reach the ```virgilio.log.info`` function.

```js
var myModule = function (options) {
    var virgilio = this;

    virgilio.namespace('myModule')
        .defineAction('doge', doge);

    function doge() {
        if (options.myModuleOptions.myCustomOption) {
            virgilio.log.info('myModule.doge called');
            return 'such action';
        }
    }
};

var virgilio = require('virgilio')(options);

virgilio.loadModule(myModule);

virgilio.execute('myModule.doge')
    .then(function (result) {
        console.log(result);
    })
    .done();
```

We can solve this simple exposing the 'log' function in the root namespace.