Booleans page should show truthy, falsy and invalid

[andylolz]

The dashboard boolean page lists False and True values alongside 0, 1, false and true. This is potentially confusing, since False and True (i.e. title case) are in fact invalid values according to the XML spec.

It might be better to either:

1. ignore any values that are not 0, 1, false or true, or
2. group invalid values as invalid.

This is exacerbated by the table column sort, which is case insensitive, so treats False and True as if they’re the same as false and true.

[andylolz]

e06ba00 addresses the sort order issue.