Include predicate for lazily added boolean accessors

Previously, the value of whatever accessor was missing was left out of
the call to build it. This had the effect of skipping over the
lazily-built predicate method when the missing accessor is for a
boolean.

Of course, I realize this all is a bit contrived as most of the time
folks aren't assigning these values manually to stripe objects. However,
in my testing it caught me by surprised that the behavior is asymmetric
depending on how and when values are assigned.

As such I believe this is a less surprising implementation.

lib/stripe/stripe_object.rb

@@ -262,9 +262,10 @@ module Stripe
       # TODO: only allow setting in updateable classes.
       if name.to_s.end_with?('=')
         attr = name.to_s[0...-1].to_sym
+        val = args.first
 
         # the second argument is only required when adding boolean accessors
-        add_accessors([attr], {})
+        add_accessors([attr], { attr => val })
 
         begin
           mth = method(name)

test/stripe/stripe_object_test.rb

@@ -80,6 +80,13 @@ module Stripe
       refute obj.respond_to?(:not_bool?)
     end
 
+    should "assign question mark accessors for booleans added after initialization" do
+      obj = Stripe::StripeObject.new
+      obj.bool = true
+      assert obj.respond_to?(:bool?)
+      assert obj.bool?
+    end
+
     should "mass assign values with #update_attributes" do
       obj = Stripe::StripeObject.construct_from({ :id => 1, :name => 'Stripe' })
       obj.update_attributes(:name => 'STRIPE')