Merge "internal test framework files for standardization of is_not/not_in;"

diff --cc lib/sqlalchemy/testing/__init__.py
Simple merge

diff --cc lib/sqlalchemy/testing/assertions.py
Simple merge

diff --cc test/engine/test_execute.py
Simple merge

diff --cc test/ext/test_baked.py
Simple merge

diff --cc test/orm/test_transaction.py
Simple merge

diff --cc test/sql/test_operators.py
Simple merge