## 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
def __init__(self, klass):
        self.klass = klass
        self.instance = None
    def __call__(self, *args, **kwds):
        if self.instance is None:
            self.instance = self.klass(*args, **kwds)
        return self.instance
def get_machine_id() -> str:
    """A MAC address-dependent ID. Useful for PostHog instance analytics."""
    
    
    return hashlib.md5(uuid.getnode().to_bytes(6, "little")).hexdigest()
def get_table_size(table_name) -> str: