Remove Deprecated EmailValidator

[JDutil]

Description

The email validator was deprecated Mar 15th 2018 almost 18 months ago
as part of: 6d8fd3c

The deprecation warning was part of v2.6.0rc1, and remains to this day
in v2.10.0.beta1 I think it's time to remove it altogether. It's been
4 minor version upgrades now.

Fixes #1794

Checklist:

• I have followed Pull Request guidelines
• I have added a detailed description into each commit message
• I have updated Guides and README accordingly to this change (if needed)
• I have added tests to cover this change (if needed)

[tvdeyen]

I am 👍 but for the record not Spree::EmailValidator has been deprecated but the namespace-less EmailValidator is deprecated.

Still I think we should not validate emails in core, but within extensions like solidus_auth_devise.

[spaghetticode]

While I agree it's ok to remove EmailValidator, I'm not sure about completely removing the email validator Spree::EmailValidator as well.

I think a more conservative approach may be to deprecate Spree::EmailValidator first, as somebody may be using it, and remove it with a later version of Solidus.

[kennyadsl]

I'm in favor of removing the deprecation warning but I think this will cut a whole feature off and users could be currently relying on that validation.

EmailValidator is just proxying through ActiveSupport::Deprecation to print a message but we are still currently using `Spree::EmailValidator', we could remove the deprecation though.

If we want to remove the validation or move it into solidus_auth_devise I think we need a more complex plan. I think an initial good solution for this could be using a preference like Spree::Config.email_validation_class providing a simple solution as a default, but allowing users to create extensions that replace the simple implementation with something better. What do you think?

[JDutil]

@kennyadsl updated 👍

[kennyadsl]

I think specs are failing due to the core/lib/spree/core/validators/email.rb → core/lib/spree/validators/email.rb rename, which should not happen. Also, can you please remove the changelog entry? It will be autogenerated using the PR title, so it's better to change it and remove the entry, thanks!

[JDutil]

@kennyadsl updated 👍

[kennyadsl]

Thanks, @JDutil!