Custom JS/HTML in Header and Footer

As an Admin I'd like to be able to put any JS/HTML I want on top and in the bottom of pages so that I'm able to post adds/counters there

Acceptance Tests:

• Given I'm granted to ADMIN permissions for JCommune component, I can see buttons "Add Custom HTML/JS here" in each highlighted box
• Given I've added HTML/JS, there it is displayed on each page of the forum.
• Given I've opened editing form, I have Cancel and Save buttons.
• Sample-sections.sql script should be amended to grant permissions for default user.

Criteria on labels:

• If banner is empty, then button on page should be labeled with 'Add' (Добавить, Додати)
• If banner is not empty, then button on page should be labeled with 'Edit' (Редактировать, Редагувати)
• In modal dialog for banner uploading there is always Save(Сохранить, Зберегти)/Cancel(Отменить, Відмінити) buttons, they don't change labels.

Dialog title:

• Paste your HTML/JavaScript here:
• Вставьте свой HTML/JavaScript код сюда:
• Вставте свій HTML/JavaScript код сюди: