Fix from header in mail when utf8 characters are used

When UTF8 characters are used in name or site name, from header is utf8 encoded but quotes are needed or header will be wrong.

Without quotes I get:
=?UTF-8?Q?Pedro_ [Ib=C3=A9rica_de_Sales_S.A.] _ <pedro@programatica.es>,
	?=@programatica.es

With quotes I get:
=?UTF-8?B?cGl0ZXIgW0liw6lyaWNhIGRlIFNhbGVzIFMuQS5d?= <pedro@programatica.es>

In 2.0 it worked because it was quoted like this:
"\"#{Refinery::Core.site_name}\" <no-reply@#{request.domain}>"
Merge pull request #136 from pedropaG/patch-1

Fix from header in mail when utf8 characters are used