Tests from some integration test classes should be moved into integration for specific BaseClient methods

[r24mille]

Some integration test classes are comprised of basic calls to the BaseClient methods they implement, checking that the network request worked and response content was able to be parsed. These standard request/response checks for each BaseClient methods exist centrally in test_genmix.py, test_lmp.py, test_load.py, test_trade.py, and test_tasks.py.

These specific integration test classes should have their basic checks moved:

• integration_test_aeso.py
• integration_test_nbpower.py
• integration_test_sask.py