Add new field to ViewAccess and TemplateAccess

[vicente-ramos]

Add to both model next generic fields:
• description (text)
• created (datetime)
• updated (datetime)

ViewAccess data model can add next fields:
#: Description for the view access restriction.

#: When view access was created.

#: When was the last update of the view access.

TemplateAccess data model can add next fields:
#: Description for the template tag restriction.

#: When template tag was created.

#: When was the last update of the template tag.