Fix Style/Not cop violations

spec/support/select2_helper.rb

@@ -12,9 +12,9 @@
 
 module Select2Helper
   def select2(value, options={})
-    raise "Must pass a hash containing 'from'" if not options.is_a?(Hash) or not options.has_key?(:from)
+    raise ArgumentError, 'options must be a Hash' unless options.kind_of?(Hash)
 
-    selector = options[:from]
+    selector = options.fetch(:from)
 
     if options[:multiple]
       execute_script("$('#{selector}').select2('val', ['#{value}'], true);")