added container hooks

[josephmancuso]

This PR adds new container hooks.

The three hooks are:

• on bind
• on make
• on resolve

you can set various bindings on the container through classes or strings. An example would be to add a binding on the container whenever you make the Request object. This is awesome for testing purposes:

def set_path_on_request(self, request, container)
    request.path = '/anewroute'
    print('YAY')

...

def boot(self):
    self.on_make(Request, set_path_on_request)

---

NOTE:

The container hook is always passed 2 parameters: the object bing binded or made or resolved, and the container. So anytime you make a function for a hook, it needs those 2 parameters.

---

Now everytime in your application you "make" the Request object through self.app.make('Request') or something similar, you will fire that function.

This is the same for bind and resolve:

def boot(self):
    self.on_make(Request, set_path_on_request)
    self.on_bind(Request, set_path_on_request)
    self.on_resolve(Request, set_path_on_request)

You can also have a bunch of these since it's just building a dictionary:

def boot(self):
    self.on_resolve(Request, set_path_on_request)
    self.on_resolve(User, set_path_on_request)
    self.on_resolve(View, set_path_on_request)

[coveralls]

Coverage increased (+0.06%) to 91.64% when pulling 0abf010 on add-container-hooks into 2faae99 on master.