## Bug description

We've had a user create a funnel with Korean characters and 17 steps, which causes this issue:
![image](https://user-images.githubusercontent.com/1727427/120301818-8c212a00-c2cd-11eb-8b00-7ba242e4a9ab.png)

## Expected behavior

We should send requests to api/insight/funnel using POST instead of GET.

## How to reproduce

1.
2.
3.

## Environment

- [ ] PostHog Cloud
- [ ] self-hosted PostHog, version/commit: _please provide_

## Additional context



#### *Thank you* for your bug report – we love squashing them!

posthog/utils.py
""" use requestobject to fetch client machine's IP Address """
    x_forwarded_for = request.META.get("HTTP_X_FORWARDED_FOR")
    if x_forwarded_for:
        ip = x_forwarded_for.split(",")[0]
    else:
        ip = request.META.get("REMOTE_ADDR")  
    return ip
def dict_from_cursor_fetchall(cursor):
    columns = [col[0] for col in cursor.description]
    return [dict(zip(columns, row)) for row in cursor.fetchall()]
def convert_property_value(input: Union[str, bool, dict, list, int]) -> str:
    if isinstance(input, bool):
        if input is True:
            return "true"
        return "false"
    if isinstance(input, dict) or isinstance(input, list):
        return json.dumps(input, sort_keys=True)
    return str(input)
def get_compare_period_dates(