Role based user list blocks don't work at all

Issue Summary

If you save the settings page with no per-role lists, a single Users with <em></em> block appears in the list of blocks. If you have one or more per-role lists, they are displayed in the list of blocks as Users with <em>rolename</em>. In both cases, enabling the blocks gives you a block with the title "Users who have contributed at least one" instead of the role based list.

Looking at the code, it seems that at some point the variables were changed to store 'key' => boolean instead of a list of enabled values, or something like that, because the same error occurs in several different places. The attached patch fixes as many as I found.