Add test for dealing with fields that are unique and inactive.

At version 0.21, this dies with a moose delegation failure as there
is no result object for errors to be delegated to.
Ensure field is active and has a result before checking for errors.

Fields delegate error related methods to their result object. If a field
has no result, calling methods such as 'has_errors' dies with a Moose
delegation.

Check the field is active and has a result before checking if it has
errors. This is the same approach taken in
  HTML::FormHandler::Fields::_fields_validate
before deferring to the fields validate function.
Merge pull request #7 from veryrusty/bugfix/unique-inactive-fields

Test and patch for dealing with fields that are unique and inactive
allow using arrayref for sort_column
remove catalyst example; see github
bump version to 0.22
bump release to 0.23