EZP-22324: Implemented premium subscriber content

A custom location view provider displays a teasing template
if the content is Premium (section id 7 (Premium)), and if the
user doesn't have the subscriber role (id: 6)

section_id and role_id are configured in default_settings.yml.
EZP-22324: BDD tests for premium content
EZP-22324: updated premium content scenarii
Updated tag cloud tests to demo content
Merge pull request #116 from ezsystems/EZP-22324-premium_content

Implemented premium subscriber content