Extends #3 - Account verification e-mail

[bashovski]

After registration process is completed, access to website's features will be temporarily disabled until user verifies his e-mail. There will be an optional form for changing e-mail in case user has used wrong one at the registration process.

Middleware needs to be implemented in order to block access for an user.

Therefore, it is needed to implement template for (all other) e-mails, which will be constantly same, but obviously, with different content.

Structure:

Instead of using fields in users table, I'll implement another table for verifications, which will later on, be used for other operations as well.

Verification model:

id uint64
user_id uint64
verification_type int8
verification_key string
verified boolean (default: false)
created_at timestamp
updated_at timestamp

After verifying the verification, verification can be marked as verified and will be no longer interacted with.

[bashovski]

Refer to #3