Merge branch 'release/0.17.1'
Merge branch 'release/0.18.0'
Add backported futures package to requirements list in README
Add --use-mirrors to requirements installation step in .travis.yml
Switch to using multiprocessing-compatible logging.
Removing logging config stuff from run_experiment, since we're just using multiprocessing logger now.
Update changelog and version number.
Tweak travis config now that logging is much more verbose.
Merge branch 'release/0.18.1'
Merge branch 'release/0.18.1' into develop
Merge branch 'master' of github.com:EducationalTestingService/skll
Merge branch 'master' into develop
Merge branch 'develop' into feature/arff_and_csv_support

Conflicts:
	skll/data.py