Add Base class for tests

This class:
- sets up a temporary environment for each test in /tmp
- copies all files listed in TEST_FILES located in TEST_FILES_DIR (test/testing_files) to the temporary environment
- after each test destroys the temporary environment

Signed-off-by: Tomas Hozza <thozza@redhat.com>
Modify Arcvhive tests to use BaseTest class

- All operations are now done in the temporary environment,
so the tests don't leave mess in the tests directory.

Signed-off-by: Tomas Hozza <thozza@redhat.com>
Modify some utils tests to use BaseTest class

Signed-off-by: Tomas Hozza <thozza@redhat.com>