Remove domain columns from branding table

This relationship is via the `Organisation` now; we don’t use this
column to fudge a relationship based on the user’s email address and the
matching something in these columns.

migrations/versions/0287_drop_branding_domains.py

@@ -0,0 +1,27 @@
+"""
+
+Revision ID: 0287_drop_branding_domains
+Revises: 0286_add_unique_email_name
+Create Date: 2019-04-05 16:25:11.535816
+
+"""
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects import postgresql
+
+revision = '0287_drop_branding_domains'
+down_revision = '0286_add_unique_email_name'
+
+
+def upgrade():
+    op.drop_constraint('uq_email_branding_domain', 'email_branding', type_='unique')
+    op.drop_column('email_branding', 'domain')
+    op.drop_constraint('letter_branding_domain_key', 'letter_branding', type_='unique')
+    op.drop_column('letter_branding', 'domain')
+
+
+def downgrade():
+    op.add_column('letter_branding', sa.Column('domain', sa.TEXT(), autoincrement=False, nullable=True))
+    op.create_unique_constraint('letter_branding_domain_key', 'letter_branding', ['domain'])
+    op.add_column('email_branding', sa.Column('domain', sa.TEXT(), autoincrement=False, nullable=True))
+    op.create_unique_constraint('uq_email_branding_domain', 'email_branding', ['domain'])