QPID-4544: Perl bindings now support UTF8 encoding

Modifies the swig bindings to properly work with UTF8 encoded strings.

Contributed by: Jimmy Jones <jimmyjones2@gmx.co.uk>

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1445344 13f79535-47bb-0310-9956-ffa450edef68