Update libraries/joomla/mail/helper.php

JMailHelper:isEmailAddress checked the IPv4 and IPv6 address in the domain

Please check:

https://github.com/joomla/joomla-cms/pull/724
Updated the JMailHelper with the filter_var function

Please read the following URL for more information:
>  https://github.com/joomla/joomla-platform/pull/1833
Merge remote-tracking branch 'joomla/staging' into staging
Updated the JMailHelper::isEmailAddress with the filter_var
Updated the JMailHelper::isEmailAddress and more cases for test for IPv4 and IPv6
Using the standard
Merge pull request #1833 from fitorec/staging

JMailHelper:isEmailAddress checked the IPv4 and IPv6 address in the domain
Merge pull request #1 from joomla/staging

Merge source code from joomla-platform