Add token when HTML attrs are single quoted.

Hi there!

I'm working on a project that uses Mojolicious + HAML and want CSRF protection on my forms. Text::Haml spits out HTML with attributes single quoted, which CSRFDefender doesn't pick up. This patch fixes that.

I like CSRFDefender over CSRFProtect as I don't want to use TagHelper's form_for.

Let me know if there are any problems with the patch or if I can help in other ways.

Regards,
Calum