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/sdk_config.ini

@@ -38,7 +38,7 @@ log.LogLevel=FINE
 
 ;Validation Configuration
 [validation]
-; If validation is set to strict, the PPModel would make sure that
+; If validation is set to strict, the PayPalModel would make sure that
 ; there are proper accessors (Getters and Setters) for each model
 ; objects. Accepted value is
 ; 'log'     : logs the error message to logger only (default)