Add support for selectable data models

[cmlccie]

When working with the WebEx APIs, I would like to be able to specify what type/class of data objects I want returned for each of the API response object types. I might want the default objects returned, or I might want dictionary objects, or even my own ORM-mapped objects.

[cmlccie]

The coding work has been completed and released. We now need to document how to use the feature.

[cmlccie]

This functionality may be refactored in v2.x. Let's document and release this functionality in v2 when the feature stabilizes.