added alembic config for DB.
added owner_id to bundles with migrations.
updated read me with db instructions
updating the readme some and fix for setup.
fix for OSX in session_name
Merge branch 'refs/heads/upstream/master' into feature/Migrations

Conflicts:
	codalab/model/tables.py
	codalab/objects/bundle.py
	setup.sh
Merge pull request #80 from codalab/feature/Migrations

db migrations and sample migration - issue #62
quick fix for issue # #83 with migrations

the problem comes from construct call being manually created.
quick fix for #83 and uploaded bundles.
fix for tests.
clean up documentation about migrations
Merge branch 'master' into pliang