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

tests/PayPal/Test/Functional/resources/BillingPlansFunctionalTest/testUpdateChangingPD.json

@@ -0,0 +1,41 @@
+{
+    "description" : "Patch operation for changing payment definition values",    
+    "title" : "Patch operation for payment definition",
+    "runnable" : true,
+    "operationId" : "plan.update", 
+    "user" : { 
+        "scopes" : [ "https://uri.paypal.com/services/subscriptions"]  
+    },
+    "credentials" : {         
+        "oauth": {
+            "path" : "/v1/oauth/token",  
+            "clientId":"",    
+            "clientSecret":""
+        }
+    },
+    "request" : {
+        "path" : "v1/payments/billing-plans/{PLAN-ID}/",
+        "method" : "PATCH",
+        "headers" : {},
+        "body" : 
+        [    
+	  {
+	    "op":"replace",
+	    "path":"/payment-definitions/PD-4816080302132415WUQBT7WA",
+	    "value" : {
+	   	        "name": "Updated Payment Definition",            
+	                "frequency": "Day",
+	                "amount": {
+	                   "currency": "USD",
+	                   "value": "1"
+	                 }
+	  	      }
+	    }  
+  	]
+    },
+    "response" : {
+        "status" : "200 OK",
+        "headers" : {},
+        "body" : { }
+    }
+}