Bugs in included Sample Application

While playing with the included sample application, I found and fixed a few bugs with it.

1. The parameters were defined as strings even if the model said that they should be integers
2. The err method that was created didn't handle all the types of error objects the app threw
3. The findByStatus and findByTags methods incorrectly always routed to the basic /pet/{petId} route
4. The addPet / updatePet wouldn't return
5. Error: Can't set headers after they are sent. was thrown if a bad value was given to the basic get pet method
6. The findByTags method accidentally used a variable called data when the variable should have been output