Refactor STPTestPaymentAuthorizationViewController to be more fully-featured

This updates both STPTestPaymentAuthorizationViewController to more closely resemble PKPaymentAuthorizationViewController and makes the example app somewhat more powerful/realistic.

@raycmorgan - we should go through this and make sure if it works similarly to PKPaymentAuthorizationViewController. I'm specifically curious about when `controller:didSelectShippingAddress` gets called, and thus how the initial array of `paymentSummaryItems` gets populated.
Thanks so much Nate!
Incidentally, since you're the first person to comment on this feature: do
you find this useful? Anything we can do to make it better?

On Thu, Oct 9, 2014 at 12:30 PM, Nate Racklyeft <notifications@github.com>
wrote:

> In Example/ApplePayStubs/STPTestAddressStore.m:
>
> > +
> > +- (ABRecordRef)contactForSelectedItemObscure:(BOOL)obscure {
> > +    id item = self.selectedItem;
> > +    ABRecordRef record = ABPersonCreate();
> > +
> > +    // address
> > +    ABMutableMultiValueRef address = ABMultiValueCreateMutable(kABDictionaryPropertyType);
> > +    CFStringRef keys[5];
> > +    CFStringRef values[5];
> > +
> > +    keys[0] = kABPersonAddressStreetKey;
> > +    keys[1] = kABPersonAddressCityKey;
> > +    keys[2] = kABPersonAddressStateKey;
> > +    keys[3] = kABPersonAddressZIPKey;
> > +    keys[4] = kABPersonAddressCountryKey;
> > +    values[0] = obscure ? CFSTR("") : CFBridgingRetain(item[@"line1"]);
>
> Done, thanks! Will send a PR if time allows.
>
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