Force the html_string become String, because it is possible like SafeButter that would cause $1 would not unavailable in the block.
Merge pull request #39 from ilake/master

Force the html_string become String, because it is possible like SafeBut...
Force localize_html_string input to string before any gsubbing
Merge pull request #42 from foraker/fix-safebuffer-handling

Force localize_html_string input to string before any gsubbing
Merge remote-tracking branch 'upstream/master'