Add a server default to the db migration

migrations/versions/ebc103f8bc5e_add_contact_info.py

@@ -18,7 +18,7 @@ depends_on = None
 
 def upgrade():
     with op.batch_alter_table('user') as batch_op:
-        batch_op.add_column(sa.Column('contact', hiboo.models.JSONEncoded(), nullable=True))
+        batch_op.add_column(sa.Column('contact', hiboo.models.JSONEncoded(), nullable=True, server_default="{}"))
 
 
 def downgrade():