Signer model has emailNotification attribute

[benoitbryon]

The emailNotification option for signers makes it possible to configure per-recipient email body, subject and language.
See reference at https://www.docusign.com/p/RESTAPIGuide/Content/REST%20API%20References/Recipients/Signers%20Recipient.htm

Important: even if in embedded signing mode (i.e. DocuSign does not send emails to recipients) language is used as the default to display DocuSign's user interface.
See http://stackoverflow.com/questions/26785088/embedded-docusign-signing-using-recipients-language

[benoitbryon]

Given:

• one recipient can have zero or one emailNotification
• emailNotification attributes do not clash with recipient attributes

Proposal: flatten emailNotification attributes into Signer model.

Example:

• strictly following DocuSign API: signer = pydocusign.Signer(emailNotification=pydocusign.EmailNotification(emailSubject='hello'))
• merging emailNotification into Signer: signer = pydocusign.Signer(emailSubject='hello')

[benoitbryon]

Given the following important notice in DocuSign's API:

[about emailNotification...]
If this is enabled for one recipient, it overrides the Envelope Subject and EmailBlurb. Also, you must enable emailNotification for all recipients.

Proposal:

• when creating envelope,
• if one signer has supportedLanguage, use it as a default value for all signers.
• if envelope has emailBlurb or emailSubject, use them as default values for signer's emailBody and emailSubject.