GH-4 Added unsupported reference warning ignore list

Fixes GitHub issue #4.
GH-4 Added unsupported reference warning ignore list

Try to fix broken syntax with old Perl <= 5.12
* https://travis-ci.org/burnersk/Encoding-HandleUtf8/jobs/41584809
* https://travis-ci.org/burnersk/Encoding-HandleUtf8/jobs/41584810
Merge pull request #5 from burnersk/feature/GH-4-unsupported-ref-ignore-list

New Feature: unsupported reference warning ignore list