Revisit email features ssl connections

[Stezido]

• [x] I have searched the issues of this repository and believe that this is not a duplicate.

Description 😯

Currently the ssl configuration regarding email notification are not possible. e.g. EMAIL_SSL is passed to the blockchain service but never used.

How to reproduce 🕹

Try to start Trubudget including the email-service. Try to configure a ssl connection from

1. blockchain to email-service
2. email-service to email-db
3. frontend to email-service

Your Environment 🌎

Tech	Version
Email-Service	v2.0.1