Increase limit of email text field to 254 characters

[rvsia]

Fixes #3677

The emails are limited to 51 characters, however they can be 254 characters long (according to documentation mentioned in the issue). Of course I don't think there could be anyone with so long email address, but it's not a bad idea to support it.

@miq-bot add_label hammer/no, rbac,

[miq-bot]

Checked commit rvsia@e15d1d6 with ruby 2.3.3, rubocop 0.52.1, haml-lint 0.20.0, and yamllint 1.10.0
1 file checked, 1 offense detected

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• 💣 💥 🔥 🚒 - Linter/Haml - Linter::Haml STDERR:

warning: parser/current is loading parser/ruby23, which recognizes
warning: 2.3.6-compliant syntax, but you are running 2.3.3.
warning: please see https://github.com/whitequark/parser#compatibility-with-ruby-mri.