expand session mock to permit validation error injection
replace group attributes with 'recognized' validations used to filter which errors trigger group error styling
test for default value of 'unchecked' (zero)
avoid comparisons where given checkbox string value are treated as integers and wrongly equated to default unchecked value, resulting in intended value being overwritten by fallback
reformulate test and suspend as proves opposite of that intended
Merge pull request #163 from petercoles/checkbox-values

User-defined checkbox values being overwritten when unchecked value is zero.
Merge pull request #162 from petercoles/group-errors

Control over which validation errors contribute to styling for Groups