Renaming Namespaces and Organizing Classes

- Updated OpenId classes to be in API namespace
- Updated PP Naming Convention to PayPal Naming Convention
- FormatConverter Class got its own namespace
- Handlers are grouped in Handler namespace
- Samples and Tests Updated Accordingly

sample/payment-experience/CreateWebProfile.php

@@ -51,7 +51,7 @@ $request = clone $webProfile;
 try {
     // Use this call to create a profile.
     $createProfileResponse = $webProfile->create($apiContext);
-} catch (\PayPal\Exception\PPConnectionException $ex) {
+} catch (\PayPal\Exception\PayPalConnectionException $ex) {
     ResultPrinter::printError("Created Web Profile", "Web Profile", null, $request, $ex);
     exit(1);
 }