Aiohttp-datadog

Allow passing a custom `dogstatsd_class` or `dogstatsd_instance`.

Use new-style middleware definition to get rid of aiohttp warnings.

:warning: Removed the Datadog tags `http_version`, `http_path`, and `request_type`.

Calculating the list of tags has been extracted to a method called `get_tags`.
If you need these (or any other tags,) you can readd them by subclassing
and overriding this method, like so:

python
class CustomDatadogMiddleware(DatadogMiddleware):

def get_tags(self, request):
tags = super().get_tags(request)
tags.append(f'http_version:{request.version}')
return tags

Added changelog entry for 0.2.0.

The kwargs passed as the second parameter are now sent to `Dogstatsd`
instead of `datadog.initialize` to expose more useful options,
such as `constant_tags`.

:warning: This means you need to update your keys
from `statsd_host` and `statsd_port` to `host` and `port`.

Initial release.