Fix #102.
Merge remote-tracking branch 'origin/demo2' into demo2
Fix test_util_test_tools.py test case failure

Clear the keystore before initializing the util_test_tools.py repository and again after every test case exits.
Merge branch 'demo2' of https://github.com/theupdateframework/tuf into demo2
Fix test_updater.py test case failure

Rebuild server repository in test_5_all_targets() - other test cases may not have properly restored the contents of the repository.
Merge branch 'demo2', remote-tracking branch 'upstream/demo2' into demo2
Add a filter to the logging console handler to simplify exception text.
Offer option to remove console handler; fix variable shadow bug.

The rest of the integration tests will need updates due to the fix of
the variable shadow bug.
Merge branch 'demo2', remote-tracking branch 'upstream/demo2' into demo2
test_mix_and_match_attack and test_indefinite_freeze_attack refactory fix