Sihl should warn if there are unapplied migrations

[aronerben]

[joseferben]

We could also improve the migration progress reporting, this could be interesting for projects with slow or a lot of migrations.

[aronerben]

@jerben You mean like a progress bar?

[joseferben]

@aronerben Yes something like that

[aronerben]

@jerben You mean like a progress bar?

Will be done at a later time

[aronerben]

@jerben You mean like a progress bar?

Will be done at a later time

Here: https://github.com/oxidizing/sihl/issues/369