New model order

This patch deprecates schema.sql and the sql/upgrades system.

Instead, we'll use SQLAlchemy models and alembic to describe the database schema, create a database initially and run migrations. 

Model and database creation are in: socorro/external/postgresql/setupdb_app.py and socorro/external/postgresql/model.py

All tables and indexes are defined in model.py

All types, views and functions (stored procedures) are defined in raw_sql/*

There's also a new directory: alembic  which contains a first draft of a new migration system and a couple example migrations.