Arvados » Arvados Workbench 2

As an admin I would like to have a list of all users
so that I can manage them

Acceptance criteria:
- tabs: Users and Activity
- table with column: First name, Last Name, UUID, Email, Active, Admin, Redirect to user, Username
- more options icon with: Attributes, Advanced, Projects, Manage
- checkboxes: "Active" "Admin" - changing the state will change the permissions
- button "+ New User" in right top corner for adding a new user
- modal for adding new user (att. admin - new user)
- validation of email field: This field is required.

Mockup: https://3czrf1.axshare.com/#g=1&p=15_5_1_admin_panel_-_users&c=1