Admin - Initial Admin/s

[fcarreno]

As a product owner, I want to have Admin user level associated to my user, so as I can perform system-wide actions

Acceptance criteria:

• System should be initialized with one (or more) users with role = 'admin'
• This story is just meant to consider that the 'role' / 'roles' attribute associated to a user, should accept the value 'admin'.
• The actual implementation of features associated to the admin role, will be implemented in other stories within the Admin milestone.