Flower: Celery's priority seperator has become configurable

[jobec]

It's now possible to configure the seperator when using Redis as a broker. See https://github.com/celery/kombu/pull/1020

This means that hard coding this separator might break things:
https://github.com/mher/flower/blob/2da8d7dbabffdb5c6fd9aa141946e1881bb9281c/flower/utils/broker.py#L101
https://github.com/mher/flower/blob/2da8d7dbabffdb5c6fd9aa141946e1881bb9281c/flower/utils/broker.py#L120

[mher]

Feel free to open a pull request

[dejlek]

Why? So that we wait for half a year for it to be reviewed and merged?

[Asday]

Why? So that we wait for half a year for it to be reviewed and merged?

... Because this is how open source works? The author of a package shouldn't have to be expected to do all the work.