Ensure @options is always set in ActiveModel::ValidationMatcher. (#1669)

This was broken by this commit. a4289e9#diff-3762aac43395307304ac640d275475f4e8512211cdd02bfcca21a1223f130d60R27

Author: yelvert

lib/shoulda/matchers/active_model/validation_matcher.rb

@@ -8,6 +8,7 @@ class ValidationMatcher
         def initialize(attribute)
           super
           @attribute = attribute
+          @options = {}
           @expects_strict = false
           @subject = nil
           @last_submatcher_run = nil