Fix error thrown when adding one-time CC.

[gordonmessmer]

This change fixes the first bug discussed here: http://requesttracker.8502.n7.nabble.com/Onetime-CC-are-giving-an-internal-error-td61678.html

[9625] [Thu Apr 7 12:37:48 2016] [warning]: Use of uninitialized value in split at /opt/rt4/share/html/Helpers/PreviewScrips line 81. (/opt/rt4/share/html/Helpers/PreviewScrips:81) [9625] [Thu Apr 7 12:37:48 2016] [error]: Operation "eq": no method found, left argument has no overloaded magic, right argument in overloaded package Email::Address at /opt/rt4/share/html/Helpers/PreviewScrips line 115.

Stack: [/opt/rt4/share/html/Helpers/PreviewScrips:115] [/opt/rt4/share/html/Helpers/autohandler:51] [/opt/rt4/sbin/../lib/RT/Interface/Web.pm:696] [/opt/rt4/sbin/../lib/RT/Interface/Web.pm:375] [/opt/rt4/share/html/autohandler:53] (/opt/rt4/sbin/../lib/RT/Interface/Web/Handler.pm:208)