This allows procedures and event hooks to have more flexible signatures.
Along the lines of:
```python
@when(SomeEvent)
def hook(event):
...
@when(SomeOtherEvent)
def hook2():
...
```
Instead of supporting only the full context spec:
```python
@when(SomeEvent)
def hook(event, **ctx):
...
```
Closes: #400
When a client triggers a `WebhookEvent` by calling a configured webhook
over `/hook/<hook_name>`, the server will now wait for the configured
`@hook` function to complete and it will return the returned response
back to the client.
This makes webhooks much more powerful, as they can be used to proxy
HTTP calls or other services, and in general return something to the
client instead of just executing actions.
- Refactored the logic for executing a request and wrapping the response common to procedures, crons and event hook decorators into platypush.common.exec_wrapper
- Added mock getvalue() method to Logger to prevent PyCharm failures in the tests when sys.stdout is redirected to the Logger object
- Using `@action` annotation to indicate methods that are allowed to be
executed as actions
- The output and errors of an action are automatically wrapped into a
`Response` object without any response build required on the plugin side