Fix Statemint

[bkchr]

We needed to fix Statemint, because at the upgrade from Shell to Statemint there was used the wrong crypto. We fixed it using this hacky pr: #867

A proper solution would now be to support running Statemint with different kind of cryptos, aka make the current version work with ed25519 and then switch over to sr25519 using a runtime upgrade.

[gilescope]

So what's left here is switching over statemint back to sr25519. Is it just setting SR versions of the initial_authorities that we need to do in the migration? (or will this have affected user key derivation on the front end?)

[bkchr]

What front end? We will need to port over the authorities and do some client side changes.

[gilescope]

Ok what client side changes do we need to make? can you point me at an example line of code of what your thinking about?

[bkchr]

There is no example code for this. We will need to be able to import blocks using sr25519 and ed25519.