Allowed Values restrictions have bugs with case sensitivity

[Rob Vesse]

Two closely related bugs:

1. @AllowedEnumValues incorrectly sets the case insensitive flag to true when actually it should be case sensitive. This results in erroneous help hints in help output stating that the values are case insensitive when this is not the case
2. @AllowedRawValues does not handle case insensitivity properly actually requiring that values be specified in lower case