Correcting validation of email addresses. The use of FILTER_VALIDATE_EMAIL suffices. Therefore, additional regex is not needed for validation. Refs. https://github.com/zikula/core/issues/1779
Commenting out regex for "url" validation, since using the filter "FILTER_VALIDATE_URL" will suffice.
Merge pull request #1821 from shefik/validate_email_address

Correcting validation of email addresses.