Add map of icons

[sveetch]

Change template for something like:

{% for icon_name,icon_values in icons.items %}${{ icon_values.class_name }}: "{{ icon_values.utf8 }}";
{% endfor %}

$icons: (
    {% for icon_name,icon_values in icons.items %}{{ icon_values.class_name }}: ${{ icon_values.class_name }},
    {% endfor %}
);

@mixin include-icons(){
    @each $name, $value in $icons {
        .#{% templatetag openbrace %}$name{% templatetag closebrace %}::before {
            content: "#{% templatetag openbrace %}$value{% templatetag closebrace %}";
        }
    }
}