Very start of schema alteration port. Create/delete model and some tests.
Add some field schema alteration methods and tests.
Merge branch 'master' of github.com:django/django into schema-alteration

Conflicts:
	django/db/backends/postgresql_psycopg2/base.py
Add M2M tests and some unique support
Add support for unique_together
Merge branch 'master' into schema-alteration
Add db_table and db_tablespace handling
First stab at MySQL support
All tests passing on MySQL
Test that unique constraints get ported with column rename
Add a SQlite backend. One test passes!
db_index alteration mostly working
Implement primary key changing
Merge branch 'master' into schema-alteration
Add some state management methods to AppCache.
Added SQLite backend which passes all current tests
Repoint ForeignKeys when their to= changes.
Add M2M repointing
Add check constraint support - needed a few Field changes
Merge branch 'master' into schema-alteration