Fix an issue where s3 might return dupilcate folders
Update logic for S3 metadata listing
Don't accept POST requests
Cors headers
More fixes for project jabberwocky
More s3 metadata fixes
Merge branch 'develop' of https://github.com/CenterForOpenScience/waterbutler into develop

Conflicts:
	tests/providers/test_s3.py
Merge branch 'develop' of https://github.com/CenterForOpenScience/waterbutler into develop