Haml: Fix problem with HTML-escaped single quotes in text fields

Haml 3.1.2 displays single quotes in FormBuilder#text_ field html escaped. You may see something like that:

David's Chapter

Looking at the page's HTML, your field's values will be doubly escaped:

<input ... value="David&amp;#x27;s Chapter" />

Updating Haml to 3.1.5 or newer Show archive.org snapshot will fix it.