add new provider_details_history table

* to be used for auditing changes to provider details
* not hooked in yet
* also made provider_details.active non-nullable. set all existing null
  provider_details.active to FALSE. none are set false on live so
  should hopefully be fairly uncontroversial
* refactored NotificationHistory.from_notification and update from noti
  to share with provider_details_history

migrations/versions/0062_provider_details_history.py

@@ -0,0 +1,38 @@
+"""empty message
+
+Revision ID: 0062_provider_details_history
+Revises: 0061_add_client_reference
+Create Date: 2016-12-14 13:00:24.226990
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '0062_provider_details_history'
+down_revision = '0061_add_client_reference'
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects import postgresql
+
+def upgrade():
+    op.get_bind()
+    op.execute('UPDATE provider_details SET active = false WHERE active is null')
+
+    op.alter_column('provider_details', 'active', existing_type=sa.BOOLEAN(), nullable=False)
+
+    op.create_table('provider_details_history',
+        sa.Column('id', postgresql.UUID(as_uuid=True), nullable=False),
+        sa.Column('display_name', sa.String(), nullable=False),
+        sa.Column('identifier', sa.String(), nullable=False),
+        sa.Column('priority', sa.Integer(), nullable=False),
+        sa.Column('notification_type', postgresql.ENUM('email', 'sms', 'letter', name='notification_type', create_type=False), nullable=False),
+        sa.Column('active', sa.Boolean(), nullable=False),
+        sa.PrimaryKeyConstraint('id')
+    )
+
+
+def downgrade():
+    op.drop_table('provider_details_history')
+
+    op.alter_column('provider_details_history', 'active', existing_type=sa.BOOLEAN(), nullable=True)
+    op.alter_column('provider_details', 'active', existing_type=sa.BOOLEAN(), nullable=True)