Fix permissions

[docwilmot]

This module's hook_permission() provides a administer blocks permission, which is already provided by core. We should either change this to a administer mini layout blocks permission or delete that implementation. If we delete, then the administer blocks permission will be the sole access control to creating and configuring Mini layouts. Are there situations where a user should have administer blocks but not be able to create a Mini block?

[yorkshire-pudding]

I can't think of any scenarios where you would grant one but not the other; the only difference is where the blocks are placed, so I think it should be safe to remove.