Update model

- adds email_from field to the service model
- adds subject_line to the template model

These are unique and not null fields, so there is a migration here for email_from to populate it.

migrations/versions/0019_unique_servicename.py

@@ -0,0 +1,22 @@
+"""empty message
+
+Revision ID: 0019_unique_servicename
+Revises: 0018_unique_emailfrom
+Create Date: 2016-02-18 11:45:29.102891
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '0019_unique_servicename'
+down_revision = '0018_unique_emailfrom'
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def upgrade():
+    op.create_unique_constraint(None, 'services', ['name'])
+
+
+def downgrade():
+    op.drop_constraint(None, 'services', type_='unique')