Refs #14 - Introduced experimental template of notification request's body.
Refs #14 - Typos in templates.
Refs #14 - Typos in templates.
Refs #14 - Typos in templates.
Refs #14 - Introduced helper functions to generate callback requests using templates. Improved template to support more events.
Refs #14 - Improved callback template. Introduced tests around DocuSignCallbackParser that use callback template.
Refs #14 - Improved tests around callback templates and parser. Declared pseudo-constants for envelope and recipient events in models.
pydocusign provides utilities to test notification callbacks: post fake callbacks using template. Closes #14, closes #16.