Method Watching Feature

Added ```hm.watchMethod(object, methodName, callback)``` to the library.

It allows you to intercept object method calls to see when they are being called in code.

Example:
```javascript

var test = {
  method: function () {
    console.log('method called');
  }
};

hm.watchMethod(test, 'method', function () {
  console.log('method intercepted');
});

test.method();

/*
 * Output:
 * method intercepted
 * method called
 */
```