Enabled Billing Plans and Agreements APIs

- Added API Classes, Samples, and Tests
- Updated Functional Tests
- Updated Documentation with new SDK Name
- Updated Few Samples to use newer nicer result page

sample/billing/CreateBillingAgreementWithPayPal.php

@@ -0,0 +1,91 @@
+<?php
+
+// # Create Billing Agreement with PayPal as Payment Source
+//
+// This sample code demonstrate how you can create a billing agreement, as documented here at:
+// https://developer.paypal.com/webapps/developer/docs/api/#create-an-agreement
+// API used: /v1/payments/billing-agreements
+
+// Retrieving the Plan from the Create Update Sample. This would be used to
+// define Plan information to create an agreement. Make sure the plan you are using is in active state.
+/** @var Plan $createdPlan */
+$createdPlan = require 'UpdatePlan.php';
+
+use PayPal\Api\Agreement;
+use PayPal\Api\Plan;
+use PayPal\Api\Payer;
+use PayPal\Api\ShippingAddress;
+
+/* Create a new instance of Agreement object
+{
+    "name": "Base Agreement",
+    "description": "Basic agreement",
+    "start_date": "2015-06-17T9:45:04Z",
+    "plan": {
+      "id": "P-1WJ68935LL406420PUTENA2I"
+    },
+    "payer": {
+      "payment_method": "paypal"
+    },
+    "shipping_address": {
+        "line1": "111 First Street",
+        "city": "Saratoga",
+        "state": "CA",
+        "postal_code": "95070",
+        "country_code": "US"
+    }
+}*/
+$agreement = new Agreement();
+
+$agreement->setName('Base Agreement')
+    ->setDescription('Basic Agreement')
+    ->setStartDate('2015-06-17T9:45:04Z');
+
+// Add Plan ID
+// Please note that the plan Id should be only set in this case.
+$plan = new Plan();
+$plan->setId($createdPlan->getId());
+$agreement->setPlan($plan);
+
+// Add Payer
+$payer = new Payer();
+$payer->setPaymentMethod('paypal');
+$agreement->setPayer($payer);
+
+// Add Shipping Address
+$shippingAddress = new ShippingAddress();
+$shippingAddress->setLine1('111 First Street')
+    ->setCity('Saratoga')
+    ->setState('CA')
+    ->setPostalCode('95070')
+    ->setCountryCode('US');
+$agreement->setShippingAddress($shippingAddress);
+
+// For Sample Purposes Only.
+$request = clone $agreement;
+
+// ### Create Agreement
+try {
+    // Please note that as the agreement has not yet activated, we wont be receiving the ID just yet.
+    $agreement = $agreement->create($apiContext);
+
+    // ### Get redirect url
+    // The API response provides the url that you must redirect
+    // the buyer to. Retrieve the url from the $agreement->getLinks()
+    // method
+    foreach ($agreement->getLinks() as $link) {
+        if ($link->getRel() == 'approval_url') {
+            $approvalUrl = $link->getHref();
+            break;
+        }
+    }
+
+} catch (PayPal\Exception\PPConnectionException $ex) {
+    echo "Exception: " . $ex->getMessage() . PHP_EOL;
+    var_dump($ex->getData());
+    exit(1);
+}
+
+ResultPrinter::printResult("Created Billing Agreement. Please visit the URL to Approve.", "Agreement", "<a href='$approvalUrl' >$approvalUrl</a>", $request, $agreement);
+
+return $agreement;