## 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
from posthog.models import Team
    template = get_template(template_name)
    
    team: Optional[Team] = None
    try:
        team = request.user.team  
    except (Team.DoesNotExist, AttributeError):
        team = Team.objects.first()
    context["self_capture"] = False
    context["opt_out_capture"] = os.getenv("OPT_OUT_CAPTURE", False)
    if os.environ.get("SENTRY_DSN"):
        context["sentry_dsn"] = os.environ["SENTRY_DSN"]
    if settings.DEBUG and not settings.TEST:
        context["debug"] = True
        context["git_rev"] = get_git_commit()
        context["git_branch"] = get_git_branch()
    if settings.SELF_CAPTURE:
        context["self_capture"] = True
        if team:
            context["js_posthog_api_key"] = f"'{team.api_token}'"
            context["js_posthog_host"] = "window.location.origin"
    else:
        context["js_posthog_api_key"] = "'sTMFPsFhdP1Ssg'"
        context["js_posthog_host"] = "'https://app.posthog.com'"
    context["js_capture_internal_metrics"] = settings.CAPTURE_INTERNAL_METRICS
    html = template.render(context, request=request)
    return HttpResponse(html)
def friendly_time(seconds: float):