• Add verifySubscriptions method to check all subscriptions in a group at once (#333, related issue: #194)
• Rename verifySubscription(type:productId:inReceipt:validUntil:) to verifySubscription(ofType:productId:inReceipt:validUntil:) (#333)
• Add video tutorials section in README (#328, #330, see #326)
• Update iOS Demo App (#327, see #147)