add new service whitelist table

services can have a whitelist of phone numbers and email addresses that they
can send to in addition to team members when in trial mode. email_address
and mobile_number are nullable and app level checks will be in place to
prevent inserting blank rows. they have a created_at date so that we can
[potentially] delete them a week later to avoid keeping personally identifying
data any longer than necessary

migrations/versions/0055_service_whitelist.py

@@ -0,0 +1,31 @@
+"""add service whitelist table
+
+Revision ID: 0055_service_whitelist
+Revises: 0054_perform_drop_status_column
+Create Date: 2016-09-20 12:12:30.838095
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '0055_service_whitelist'
+down_revision = '0054_perform_drop_status_column'
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects import postgresql
+
+def upgrade():
+    op.create_table('service_whitelist',
+        sa.Column('id', postgresql.UUID(as_uuid=True), nullable=False),
+        sa.Column('service_id', postgresql.UUID(as_uuid=True), nullable=False),
+        sa.Column('email_address', sa.String(length=255), nullable=True),
+        sa.Column('mobile_number', sa.String(), nullable=True),
+        sa.Column('created_at', sa.DateTime(), nullable=True),
+        sa.ForeignKeyConstraint(['service_id'], ['services.id'], ),
+        sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_service_whitelist_service_id'), 'service_whitelist', ['service_id'], unique=False)
+
+
+def downgrade():
+    op.drop_table('service_whitelist')