method for creating a SwaggerFactory; uses java.util.ServiceLoader to find a SwaggerFactory
implementation - falls back to the default implementation if none are found
Generic interface for abstracting the source of a swagger definition - allowing Swagger definitions to be read
from a non path-based storage (databases, etc)
Simple interface of abstracting the target location of a created Swagger definition, so Swagger objects
can be written to non file-based stores (databases, etc)