Add initial models and corresponding test files

spec/models/domain_spec.rb

@@ -0,0 +1,14 @@
+require "rails_helper"
+
+describe Domain do
+  it { should belong_to(:registrar) }
+  it { should belong_to(:ns_set) }
+  it { should belong_to(:admin_contact) }
+  it { should belong_to(:owner_contact) }
+  it { should belong_to(:technical_contact) }
+
+  it 'creates a resource' do
+    d = Fabricate(:domain)
+    expect(d.name).to_not be_nil
+  end
+end