Makes PresentationCondition and FeedbackCondition regexps case-insensitive

This PR will help prevent users from accidentally failing to match their PCs and FCs due to case.

Anywhere the user enters a label (aka 'tag') in a form, it is internally converted to lowercase:
```ruby
ActsAsTaggableOn.force_lowercase = true
```
but the string displayed to the user is not.  This causes user confusion when forming PC and FC regexps, since they are unaware of the internal change.  To mitigate this problem, the regexps used in PC and FC matching are made case-insensitive:
```ruby
label == regex || label.match(Regexp.new(regex, Regexp::IGNORECASE))
```