[Organization - Emails] Prototype - Override the default email provider

[alexchiraples]

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Migrated from https://github.com/gov-ithub/auth-sso/issues/54
Originally created by @alexchiraples on Tue, 15 Nov 2016 14:05:18 GMT

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The default email settings should be stored in the database instead of configuration file.
As an organization admin, I need to be able to use my own email provider and settings and not the application default.

Tasks:

• Create a table for Email Provider, store settings as JSON (example Postmark and SMTP)
• Add step for initializing providers (insert if no record)
• Create a table for Email Settings with a reference to Organization and Email Provider
• When installing the system for the first time, you will need to add details for configurating the default email configuration (add a step in readme.md to insert in email settings)
• You will not be able to see email settings of the parent organization
• The email settings will be persisted with a reference to current Organization
• Create a factory for returning the assigned provider for the organization. If none found, search for parent