Fixed topic slashes on Windows & Forward bug

This PR fixes two issues:

1. ```PrefixAscoltatore.prototype._localToParent``` incorrectly generates the prefixed topic when the broker is running in a Windows environment. ```path``` changes the the direction of the slashes.

2. The next one isn't so straight forward and is actually more a bug with Mosca. When used in Mosca,  ```PrefixAscoltatore.prototype.wrapCallback``` requires a third parameter, ```options```. 

Without it, the following error is thrown in Mosca:

```
C:\nodeprojects-other\mosca\lib\client.js:172
    if (options._dedupId === undefined) {
               ^
TypeError: Cannot read property '_dedupId' of undefined
    at Client.forward (C:\nodeprojects-other\mosca\lib\client.js:172:16)
    at handler (C:\nodeprojects-other\mosca\lib\client.js:340:10)
    at Array.callback._prefix_ascoltatore_wrapper [as 0] (C:\nodeprojects-other\mosca\node_modules\ascoltatori\lib\prefix_acoltatore.js:34:7)
    at EventEmitter.TrieAscoltatore.publish (C:\nodeprojects-other\mosca\node_modules\ascoltatori\lib\trie_ascoltatore.js:52:11)
    at EventEmitter.newPublish (C:\nodeprojects-other\mosca\node_modules\ascoltatori\lib\abstract_ascoltatore.js:122:20)
    at Object._onImmediate (C:\nodeprojects-other\mosca\node_modules\ascoltatori\lib\mqtt_ascoltatore.js:72:27)
    at processImmediate [as _immediateCallback] (timers.js:317:15)
```

The error is thrown if a message is published to a Child Broker and the Child Broker has subscribers to that message.

To recreate, start in the ```examples/mosca-tree```

Run ```mosca -c firsConfig.js -v```
Run ```mosca -c secondConfig.js -v```
Run ```mosquitto_sub -p 4883 -t "/#" -v```
Run ```mosquitto_sub -p 4883 -t "hello/world" -v```
Run ```mosquitto_pub -t "hello/world" -m "dd" -p 4885```