[C++][RESTSDK] support enums (#2749)

* Support enums

* Updating petstore sample

* Use enum class instead of just enum

* Use string_t for g++ compatibility

* Add enum descriptions

* Fix string parsing. Make g++ compatible.

samples/client/petstore/cpp-restsdk/model/Pet.h

@@ -31,6 +31,7 @@ namespace openapitools {
 namespace client {
 namespace model {
 
+
 /// <summary>
 /// A pet for sale in the pet store
 /// </summary>
@@ -119,6 +120,7 @@ protected:
     bool m_StatusIsSet;
 };
 
+
 }
 }
 }