Feature request: Pluggable resourceful routing definition

In current Chalice, we usually need to define some conditions if we make an endpoint handle various HTTP methods just like following,

```python
@app.route('/', methods=['GET', 'POST'])
def index():
method = app.current_request.method

if method == 'GET':
pass

if method == 'POST':
pass
```

However I guess it can lose readability in some cases
And it would be worse if it needs to handle all CRUD with a single endpoint

Thus, althogh I would be happy if I can define an endpoint like below, what do you think about it? Do you have any plan to support pluggable or classified view definition?

```python
@app.route('/')
class Index(View):
def get(self):
pass

def post(self):
pass
```

or

```python
class Index(View):
def get(self):
pass

def post(self):
pass

app.register_route(Index, '/')
```

or both :)
I prefer the latter one

This looks similar to https://github.com/aws/chalice/issues/487, but I guess slightly difference
As of today, Chalice supports blueprints (as experimental API though), I think development efficiency should be improved if classified view definition and devided routing definition are supported as in the latter example

Read the related discussion in issue #487 and review Chalice's experimental blueprint support first. Compare the proposed @app.route class form with the preferred app.register_route(Index, '/') form, then clarify the routing and view-definition requirements; done means an agreed design and implementation scope for classified HTTP-method handlers.

Written by the indexing model from the issue text.