[Notifications] Ability to brand Canvas notifications

[lmorrow1]

Notifications sent via Canvas are currently not able to be branded.  This means that the emails sent to parents and students currently include the Canvas name and logo. This can cause some confusion with the community as it has no direct tie to the school or organisation and has no consistency with the site or school branding.

Having the ability to apply custom branding to email notifications at the account and sub-account level would solve this issue.  I propose that we have the following options via the theme editor to customise the following areas of notifications.

• Add the name of the organisation and the email address the notification is sent from
• Ability to add the organisations' logo
• Ability to edit the layout and colour scheme