Suppres regex warnings on utf-8 chars (1.9 only)

This works around a regexp error that comes up when parsing UTF-8
characters, which is common when dealing with comments on GitHub pull
requests:

````
./gems/simple-rss-ef0d5db568fa/lib/simple-rss.rb:155:
warning: regexp match /.../n against to UTF-8 string
````
Snag those other /u's
Merge pull request #13 from todb-r7/fix-regexp-warning

Fix regexp warning on UTF-8 characters