Assign user_roles as array rather than string

This makes it possible to push more values later on.

_includes/badges_push_dynamic.html

@@ -2,22 +2,22 @@
 {% if user_roles %}
 {% assign user_roles = user_roles | push: 'author' %}
 {% else %}
-{% assign user_roles = 'author' %}
+{% assign user_roles = 'author' | split: "|" %}
 {% endif %}
 {% endif %}
 
 {% if project_maintainers contains user_username %}
 {% if user_roles %}
 {% assign user_roles = user_roles | push: 'project-maintainer' %}
 {% else %}
-{% assign user_roles = 'project-maintainer' %}
+{% assign user_roles = 'project-maintainer' | split: "|" %}
 {% endif %}
 {% endif %}
 
 {% if project_contributors contains user_username %}
 {% if user_roles %}
 {% assign user_roles = user_roles | push: 'project-contributor' %}
 {% else %}
-{% assign user_roles = 'project-contributor' %}
+{% assign user_roles = 'project-contributor' | split: "|" %}
 {% endif %}
 {% endif %}