create, edit and use email branding instead of organisation

notable things that have been kept until migration is complete:

* passing in `organisation` to update_service will update email branding
* both `/email-branding` and `/organisation` hit the same code
* service endpoints still return organisation as well as email branding

tests/app/email_branding/test_rest.py

@@ -0,0 +1,113 @@
+import pytest
+
+from app.models import EmailBranding
+
+
+def test_get_email_branding_options(admin_request, notify_db, notify_db_session):
+    email_branding1 = EmailBranding(colour='#FFFFFF', logo='/path/image.png', name='Org1')
+    email_branding2 = EmailBranding(colour='#000000', logo='/path/other.png', name='Org2')
+    notify_db.session.add_all([email_branding1, email_branding2])
+    notify_db.session.commit()
+
+    email_branding = admin_request.get(
+        'email_branding.get_email_branding_options'
+    )['email_branding']
+
+    assert len(email_branding) == 2
+    assert {
+        email_branding['id'] for email_branding in email_branding
+    } == {
+        str(email_branding1.id), str(email_branding2.id)
+    }
+
+
+def test_get_email_branding_by_id(admin_request, notify_db, notify_db_session):
+    email_branding = EmailBranding(colour='#FFFFFF', logo='/path/image.png', name='My Org')
+    notify_db.session.add(email_branding)
+    notify_db.session.commit()
+
+    response = admin_request.get(
+        'email_branding.get_email_branding_by_id',
+        _expected_status=200,
+        email_branding_id=email_branding.id
+    )
+
+    assert set(response['email_branding'].keys()) == {'colour', 'logo', 'name', 'id'}
+    assert response['email_branding']['colour'] == '#FFFFFF'
+    assert response['email_branding']['logo'] == '/path/image.png'
+    assert response['email_branding']['name'] == 'My Org'
+    assert response['email_branding']['id'] == str(email_branding.id)
+
+
+def test_post_create_email_branding(admin_request, notify_db_session):
+    data = {
+        'name': 'test email_branding',
+        'colour': '#0000ff',
+        'logo': '/images/test_x2.png'
+    }
+    response = admin_request.post(
+        'email_branding.create_email_branding',
+        _data=data,
+        _expected_status=201
+    )
+    assert data['name'] == response['data']['name']
+    assert data['colour'] == response['data']['colour']
+    assert data['logo'] == response['data']['logo']
+
+
+def test_post_create_email_branding_without_logo_is_ok(admin_request, notify_db_session):
+    data = {
+        'name': 'test email_branding',
+        'colour': '#0000ff',
+    }
+    admin_request.post(
+        'email_branding.create_email_branding',
+        _data=data,
+        _expected_status=201,
+    )
+
+
+def test_post_create_email_branding_without_name_or_colour_is_valid(admin_request, notify_db_session):
+    data = {
+        'logo': 'images/text_x2.png'
+    }
+    response = admin_request.post(
+        'email_branding.create_email_branding',
+        _data=data,
+        _expected_status=201
+    )
+
+    assert response['data']['logo'] == data['logo']
+    assert response['data']['name'] is None
+    assert response['data']['colour'] is None
+
+
+@pytest.mark.parametrize('data_update', [
+    ({'name': 'test email_branding 1'}),
+    ({'logo': 'images/text_x3.png', 'colour': '#ffffff'}),
+])
+def test_post_update_email_branding_updates_field(admin_request, notify_db_session, data_update):
+    data = {
+        'name': 'test email_branding',
+        'logo': 'images/text_x2.png'
+    }
+    response = admin_request.post(
+        'email_branding.create_email_branding',
+        _data=data,
+        _expected_status=201
+    )
+
+    email_branding_id = response['data']['id']
+
+    response = admin_request.post(
+        'email_branding.update_email_branding',
+        _data=data_update,
+        email_branding_id=email_branding_id
+    )
+
+    email_branding = EmailBranding.query.all()
+
+    assert len(email_branding) == 1
+    assert str(email_branding[0].id) == email_branding_id
+    for key in data_update.keys():
+        assert getattr(email_branding[0], key) == data_update[key]