Don't escape slash with dynamic attributes

[k0kubun]

ref: #27

This PR fixes following inconsistent behavior.

$ cat in.haml
%a{ href: 'http://example.com' }
%a{ {}, href: 'http://example.com' }
$ bundle exec faml render in.haml
<a href='http://example.com'></a>
<a href='http:&#47;&#47;example.com'></a>

Since houdini_escape_html sets 1 as houdini_escape_html0's argument secure, it escapes "/".
I think Faml::AttributeBuilder should not escape "/". So I changed it to use houdini_escape_html0 and set secure argument to 0.

[eagletmt]

😨 https://github.com/judofyr/temple/blob/v0.7.6/lib/temple/utils.rb#L27

[eagletmt]

Released v0.3.6 💎

[k0kubun]

✨