Merge pull request #680 from mdboom/misc/remove_futures_tests

Remove tests for futures
Add "unclosed file detection" to the testing framework.

Fix unclosed file bug in logger.py
Fix unclosed file bug in wcs.
Fix unclosed file bug in io.ascii.
Add open_file_detection_test
Update to alternate implementation that uses lsof
Check that we can successfully run lsof
Python 3 fixes
Fix for Python 3.x (to do bungled rebase)